1. To determine resistivity of two / three wires by plotting a graph for
potential difference versus current.
1. Define Ohm’s law.
Answer. The current flows through conductors is directly proportional to the voltage
applied. The voltage across a conductor is directly proportional to the current flowing through
it, provided all physical conditions and temperatures remain constant.
2. What is the formula of Ohm’s law?
Answer. Ohm’s law is given by the formula: V=IR
Where, I=current, V=voltage, and R=Resistance.
3. What is specific resistance?
Answer. The resistance offered per unit length and unit cross-sectional area when a known
amount of voltage is applied is known as the specific resistance. S.I unit ohm-meter
4. What is the SI unit of the potential difference?
Answer. The SI unit of the potential difference is volt.
5. The current is measured in which unit? And which instrument
Answer. The unit of electric current is Ampere and Ammeter
6. What is the unit of resistance?
Answer. The unit of the electrical resistance is Ohms.
7. Does the resistance depend on the temperature?
Answer. Yes, the resistance depends on the temperature. As the temperature increases, the
resistance also increases for conductor.
8. What are the various sources of error while performing this experiment?
Answer: Various sources of error are:
The instrument screws may be loose.
Lack of thick connecting wires.
Using rheostat of high resistance.
9. What is electrical conductivity?
Answer. It is the measure of the ability of the material to allow the electric current to pass
through it.
10. Define a rheostat.
Answer. A rheostat is a two-terminal electrical device. The rheostat is a variable resistor
whose resistance can be changed to change the current flowing amount through a circuit.
11. State true or false: The potential difference across the wire varies linearly with the current.
Answer. TRUE. The potential difference across the wire varies linearly with the current.
12. Does the resistance depend on the dimensions of the conductor?
Answer. Yes, the resistance depends on the dimensions of the conductor.
R = ρ l/A
2. To find resistance of a given wire / standard resistor using metre
bridge.
Q1. Why is the metre bridge called so?
Ans: It is called a metre bridge because the bridges use one-meter long wire.
Q2. What is the null point?
Ans: Null point is defined as the point at which a galvanometer reads 0 deflections.
Q3. Why is the bridge method better than the Ohms law of measurement?
Ans: Bridge method is better than the Ohms law of measurement because of the null
method.
Q4. What is the range of measurement of resistance using a Wheatstone bridge?
Ans: The resistance measurement range using a Wheatstone bridge is between 1Ω to a
few megaohms.
Q5. How can a Wheatstone bridge be used for the measurement of physical
parameters?
Ans: Wheatstone bridge is used to measure the physical parameters like temperature,
light, etc, using an operational amplifier and rectifiers are used for the conversion of
A.C to D.C.
3. To verify the laws of combination(series) of resistances using a metre
bridge.
1) What is a metre bridge?
A slide wire bridge, also termed a metre bridge, is an instrument that works on the
principal Wheatstone bridge. To find unknown resistance of a conductor, a metre
bridge is used.
2) In a series combination of resistance, how do you find the equivalent
resistance?
Since the same current passes through each resistor in series combination, the total
resistance RT can be calculated using the below equation:
RT = R1+ R2 + R3 + …….Rn
3) What is Wheatstone bridge?
A Wheatstone bridge is a particular type of electrical circuit that is used in measuring
the unknown electrical resistance of the circuit by balancing the two legs of the bridge
circuit, where the unknown component includes one of its legs.
4) What is the use of a metre bridge?
To measure the resistance precisely for a resistor, a metre bridge is used.
5) Which principle is followed by the metre bridge for its working?
The principle of the Wheatstone bridge is followed by a metre bridge for its efficient
working.
6) Which material wire is used in a metre bridge?
The materials such as nichrome, constantan or manganin are used in making the wire
of a metre bridge because these materials have a high value of resistance, and the
coefficient of the temperature of their resistances is low.
7) What is the case when the metre bridge is in a more sensitive condition?
The metre bridge circuit will be very sensitive when all four resistors have the same
resistance values.
8) What is the balanced condition of a Wheatstone bridge?
When no current flows through the galvanometer, the Wheatstone bridge is said to be
in a balanced condition. By adjusting the known resistance and variable resistance,
this condition can be achieved.
9) What is the working principle of a Wheatstone bridge?
It is the principle of null deflection which is responsible for the working of a
Wheatstone bridge, i.e. no current flows through the circuit, and the ratio of their
resistances are equal.
10) What are the restrictions of Wheatstone bridge?
The resistance of the leads and contacts becomes important for low resistance
measurement, but the Wheatstone bridge shows errors while measuring them.
4. To determine resistance of a galvanometer by half- deflection method and
to find it’s figure of merit.
1. What is a galvanometer?
Answer: A galvanometer is a measuring device that measures a small electrical current or a
function of the current by deflection of a moving coil.
2. What is the formula to calculate the figure of merit of the galvanometer?
Answer: The formula to calculate the figure of merit of the galvanometer is
K= (E/R+G)/θ
.3 What is an ammeter?
Answer. An ammeter is a measuring instrument used to calculate the current in a circuit.
4. What is the unit to measure electric current?
Answer: Ampere is the unit used to measure the electric current.
6. Define ampere.
Answer: An ampere is a unit of measure of the rate of electron flow or current in an electrical
conductor.
7. How is a galvanometer converted to an ammeter?
Answer: A galvanometer is converted into an ammeter by connecting a low resistance in
parallel with the galvanometer.
8. On the galvanometer scale, why is zero placed in the middle?
Answer: Zero is placed in the middle of the galvanometer since the galvanometer needle can
deflect on both sides.
9. How is an ammeter connected in a circuit?
Answer: An ammeter should be connected in the series pattern with the circuit. When the
ammeter is placed in series, the entire current of the circuit can be calculated when it passes
through it.
10. Why is this method known as the half deflection method?
Answer: Here, the deflection is made half using a shunt resistance S. Hence It is known as the
half deflection method.
11. Are there positive and negative terminals in the galvanometer?
Answer: There are no positive and negative terminals in the galvanometer.
SECTION -B
5. To find the value of V for different values of u in case of a concave mirror
and to find the focal length.
1) What are the materials required for this experiment?
An optical bench along with three uprights, a concave mirror, a mirror holder, two
optical needles, and a half-metre scale are the materials needed for this experiment.
2) Give five main precautions that should be taken into consideration when
doing this experiment.
The uprights must always be vertical.
The mirror’s principal axis must be perpendicular, and the optical bench’s central line
must be parallel.
The observer must be a minimum of 30 cm away from the needle to find the image’s
position.
The parallax of the tip to tip must be removed between the image and the needle.
The tip of the object and the image must be at the identical height when compared to
the given mirror’s pole.
3) What are the sources of errors in this experiment?
Errors usually come as the uprights may not be vertical, and parallax corrected may
not be perfect.
4) What are the four main sections of the whole procedure in this experiment?
(a) To determine the rough focal length
(b) To set the mirror
(c) To set the object needle
(d) To set the image needle
5) What is the spherical mirror used in this experiment?
A concave mirror is a spherical mirror used in this experiment.
6) What are the two types of spherical mirrors?
Convex mirrors and concave mirrors are the two types of spherical mirrors.
7) Which type of mirror always generates a virtual image?
Convex and plane mirrors always generate virtual images.
8) What is the aperture of a spherical mirror?
The aperture of a spherical mirror is the diameter of the circular rim of a spherical
mirror.
9) Define the pole of a concave mirror?
The pole of a concave mirror is the centre point of the reflecting surface of this
mirror. It is denoted as ‘P’.
10) Define the centre of curvature on a concave mirror.
The centre of curvature is the sphere centre of which the concave mirror is a part. It is
denoted as ‘C’.
11) Define the centre of curvature on a spherical mirror.
The centre of the sphere in which the spherical mirror is a part is known as the centre
of curvature.
12) What is the correlation between the radius of curvature (R) and focal length
(F) of a concave mirror?
The correlation is given by the formula,
f = R/2.
13) Define the principal axis of a spherical mirror.
The principal axis is the imaginary line travelling through the principal axis and the
pole of the spherical mirror.
14) What is the radius of curvature of a concave mirror?
The radius of the sphere of which a concave mirror is a part is called the radius of
curvature.
15) Define the principal focus on a concave mirror.
The rays that are parallel to the concave mirror’s principal axis meet at a particular
point on the mirror’s principal axis just after the reflection. This point of convergence
is called the principal focus on a concave mirror.
16) What are the two types of lenses generally used?
Concave lenses and convex lenses are the two types of lenses generally used.
17) Is the convex lens’s focal length taken -ve or +ve?
The convex lens’s focal length is taken as positive since it meets the beam of light.
18) A convex mirror is a type of diverging mirror. Therefore, it doesn’t generate
a real focus. On the other hand, a plane mirror is not a type of diverging mirror.
Why doesn’t it generate a real focus?
As far as a plane mirror is concerned, the reflected and the incident rays form an
identical angle with the mirror. In fact, reflected rays don’t converge, and therefore, it
generates a virtual image.
19) What is the mirror formula?
The mirror formula is given by,
1/f = 1/v+1/u
f is the focal length
u is the object distance
v is the image distance
20) Define the law of reflection for mirrors?
The incident ray, the reflected ray and the normal all exist in the exact same plane.
∠i = ∠r
21) Give the number of refracting surfaces a lens possesses.
A lens has two refracting surfaces.
22) What is the ideal position of a body if you want to get an image of the same
dimension in the case of a concave mirror?
The body should be positioned at ‘C’ of a concave mirror in order to get an image of
the same dimension.
23) Which is the mirror typically used for shaving? Why?
The concave mirror is typically used for shaving. This is mainly due to the fact the
object is positioned between the focus and pole of the mirror. The resulting image will
be virtual and magnified.
24) Consider a situation where you are standing in front of a mirror, and the
image looks as follows:
The head looks to be very large, the body looks to be normal size, and the legs
look to be tiny. What is the nature of mirrors used in this scenario?
In this case, the mirror is a combination of types of mirrors. The top section is a
concave mirror, the middle section is a plane mirror, and the bottommost section is a
convex mirror.
25) What are the two main types of mirrors?
Plane mirrors and spherical mirrors are the two main types of mirrors.
26) What is denoted by the symbol ‘R’ in a concave mirror?
The radius of curvature is denoted by the symbol ‘R’ in a concave mirror.
27) Give two general uses of concave mirrors.
Concave mirrors are extensively used by dentists and in solar cookers.
28) What type of images do concave mirrors generate?
Concave mirrors generate real and virtual images.
29) If a body is at infinity, where will the image be generated in the case of a
concave mirror?
The image will be generated at the focus point of the concave mirror if a body is at
infinity.
30) When do concave mirrors produce virtual images?
Concave mirrors produce virtual when objects are positioned between the focal point
and pole.
31) What happens when parallel rays strike a convex lens?
Parallel rays converge at the focus of the convex lens.
32) When light rays pass through the optical centre of convex lenses, what
happens to the light rays?
Light rays will pass through without deviating when it passes through the optical
centre of convex lenses.
33) Do the characteristics of the images produced by convex lenses rely on the
location of the object?
Yes, convex lenses form virtual images only when positioned between the optical
centre and the focus point. In the case of all other locations, convex lenses produce
real images.
34) How will you distinguish a concave lens from a convex lens experimentally?
If the given spherical lens produces a real sharp image of a faraway object, it is a
convex lens. If not, it should be a concave lens.
35) If half of the concave lens is covered when focusing on a faraway subject,
what will be the effect on the image produced?
An image will be generated as normal, but the image intensity will be half the
original.
6. To find the focal length of a convex lens by plotting graphs between u
and v or between 1/u and1/v.
1) What is an optical aberration?
The property of the lens that causes blurriness or distortion during the formation of an image
is known as an optical aberration. The light is spread out or dispersed due to optical
aberration rather than being focused on a certain fixed point. Optical aberration is an
unwanted property of the lens, and by using a grouping of lenses rather than using a single
piece of the lens, it can be eliminated.
2) What is magnification?
Magnification of the lens is basically the ratio of the linear size of the image to the linear size
of the object.
m = (linear size of the image/linear size of the object)
3) What is a convex lens?
A lens that is curved outwards is known as a convex lens. Convex lenses are also known as
converging lenses. The thickness at the centre of a convex lens is more than its edge. A
convex lens has the capability to converge a parallel beam of light into a point.
4) What is a concave lens?
The type of lens with at least one side curved inwards is known as a concave lens. A
Biconcave lens is a concave lens with both sides curved inward. Concave lenses are also
known as diverging lenses because they spread out or diverge the rays of light that are
refracted through it.
5) Define the power of a lens?
The measure of the ability of a lens to converge or diverge the incident beam of light is
known as the power of a lens. It is given by the reciprocal of focal length.
6) What is chromatic aberration?
Dispersion is the reason why chromatic aberration occurs. Due to chromatic aberration, a lens
fails to focus all colours on the same point, and colourful fringes around an image can be
observed due to chromatic aberration. An achromatic doublet can be used to fix chromatic
aberration.
7) Define refraction.
Refraction is basically the bending of light when it passes from one medium to another.
Several devices, like microscopes, corrective lenses, magnifying lenses etc., use this property
of refraction. In this property, the polarisation of electrons takes place when the light is
transmitted through a medium, which in turn decreases the speed of light; therefore, the
direction of light changes.
8) What is total internal reflection?
When the light rays travel from a more optically denser medium to a less optically denser
medium, the phenomenon that happens is known as total internal reflection.
7. To determine angle of minimum deviation for a given prism by plotting a
graph.
1) What are the materials required for this experiment?
The materials required for this experiment are a drawing board, a white sheet of
paper, a prism, drawing pins, a pencil, a half-metre scale, office pins, a protractor, and
graph paper.
2) What is the theory behind this experiment?
Refraction happens when a light ray moves through two adjacent mediums with
different refractive indices or densities. This results in the deviation of the emergent
light ray compared to the incident light ray.
3) What is a prism?
A prism is a transparent optical device with polished, flat surfaces that refract light. At
least one of its surfaces must be angled. A similar optical device with two parallel
sides is not a prism.
4) How many edges are there in a prism?
There are nine edges in a prism.
5) What is meant by the angle of deviation?
The angle of deviation is the angle at which a light ray turns away from the original
way while moving through a prism.
6) What are the factors that control the angle of deviation?
It depends on,
i>The angle of incidence
li>The material of the prism.
<li>The refracting angle (prism).
<li>The wavelength of the light used (colour).
7) What is the angle of minimum deviation?
The minimum value of the deviation angle is called the angle of minimum deviation.
8) What is the importance of minimum deviation?
At the condition of minimum deviation, light beams move inside the prism parallel to
the prism’s base, and the angle of emergence is equal to the angle of incidence.
9) Does the colour of light influence the angle of minimum deviation?
Yes, it is varied for different wavelengths or colours.
10) Which word is used as the abbreviation for remembering the names of seven
colours in white light?
VIBGYOR is the word used for remembering the names of seven colours in white
light.
11) What is the full form of VIBGYOR?
The full form of VIBGYOR is,
Violet Indigo Blue Green Yellow Orange Red.
12) What is meant by the dispersion of light?
The process of splitting pure white light into its seven constituent colours is known as
the dispersion of light.
13) What is the conclusion of the graph of ‘i’ and ‘D’?
The deviation is minimum only at one special value of incidence angle.
14) Why are there dual values of incidence angle for one particular value of
deviation angle?
In the case where an emergent light ray is reversed, then the angle i changes to e and
the angle e changes to i. The reversed light ray will possess the exact deviation as
before.
15) Does a ray of white light produce a spectrum on travelling through a hollow
prism?
No, dispersion does not happen in the air. For the generation of the ideal spectrum,
light needs a perfect prism.
16) Which colour deviates the least?
Red colour deviates the least.
17) Which colour deviates the most?
Violet colour deviates the most.
18) Which colour possesses the highest refractive index?
Violet colour has the highest refractive index.
19) Which colour has the lowest refractive index?
Red colour possesses the lowest refractive index.
8. To draw the I-V characteristic curve for a p-n junction diode in forward
and reverse bias.
1) What are the materials required for this experiment?
A P-N junction diode, 12-volt battery eliminator , one 3-volt battery, one 0-3 volt voltmeter,
one a high resistance rheostat, one 0-100 μA ammeter, one 0-30 volt voltmeter, one 0-100
mA ammeter, connecting wires, one-way key, and sandpaper are the materials required for
this experiment.
2) Give three main precautions that should be taken while doing this experiment.
The connections must be clean, right, and neat. A key must be used while the circuit is active.
After the breakdown, voltage (forward bias) must not be provided.
3) What are the three types of materials based on electrical conductivity?
Conductors, insulators, and semiconductors are the three types of materials based on
electrical conductivity.
4) What is electrical conductivity?
Electrical conductivity is a measure of how smoothly a body allows current to move through
it.
5) What is the relationship between resistivity and electrical conductivity?
The electrical conductivity of the material is reciprocal to resistivity.
6) What is a hole in the context of a semiconductor?
A hole is a place in the crystal lattice of a material which is vacated by an electron. It is
considered a positive charge.
7) What is an intrinsic semiconductor?
An intrinsic semiconductor is a pure semiconductor that does not possess any significant
dopant species. It is also called an i-type semiconductor or undoped semiconductor.
8) What is an extrinsic semiconductor?
An extrinsic semiconductor is an impure semiconductor that possesses significant dopant
species.
9) What is an n-type semiconductor?
An n-type semiconductor is a type of intrinsic semiconductor doped using arsenic (As),
antimony (Sb) or phosphorus (P) as an impurity.
10) What is meant by doping?
Doping is the process of deliberately adding appropriate impurities to pure semiconductors.
11) What is meant by a junction?
A junction is a common surface of p-type and n-type semiconductors.
12) What is meant by a junction potential barrier?
A junction potential barrier is a potential difference between junction terminals of
semiconductors.
13) What are the two types of biasing?
Forward biasing and reverse biasing are the two types of biasing.
