Class – XII Subject: Physics Experiment (2020_21)
Exp. No Aim
Section – A
1 To determine resistivity of two / three wires by plotting a graph for potential
difference versus current.
2 To find resistance of a given wire / standard resistor using metre bridge
3 To compare the EMF of two given primary cells using potentiometer.
4 To determine resistance of a galvanometer by half-deflection method and to
find its figure of merit
Section - B
5 To find the focal length of a convex lens by plotting graphs between u and v or
between 1/u and 1/v.
6 To find the focal length of a convex mirror, using a convex lens.
7 To determine angle of minimum deviation for a given prism by plotting a
graph between angle of incidence and angle of deviation.
8 To draw the I-V characteristic curve for a p-n junction diode in forward bias
and reverse bias.
Activities
1 To measure resistance, voltage (AC/DC), current (AC) and check continuity of
a given circuit using multimeter.
2 To assemble a household circuit comprising three bulbs, three (on/off)
switches, a fuse and a power source
3 To assemble the components of a given electrical circuit
4 To identify a diode, an LED, a resistor and a capacitor from a mixed collection
of such items.
5 To observe polarization of light using two Polaroids
6 To observe diffraction of light due to a thin slit
, Experiment – 1
Aim
To determine the resistance per cm of a given wire by plotting a graph for potential difference versus
current.
Apparatus/ Material Required
A wire of unknown resistance
Battery
Voltmeter
Milliammeter
Rheostat
Plug key
Connecting wires
Piece of sandpaper
Circuit Diagram
,Theory
According to Ohm’s law, the electric current flowing through a conductor is directly proportional to the potential
difference across its ends, provided the physical state (pressure, temperature, and dimensions) of the conductor
remains unchanged.
If I is the current flowing through the conductor and V is the potential difference across its end, then
V∝I
and hence
V = RI
Where R is the constant of proportionality and is termed as the electrical resistance of the conductor.
ResistanceR depends on the dimensions and material of the conductor. The relationship between the resistance
of a material and its length and area of the cross-section is given by the formula
R=ρ / A’
Where ρ is the specific resistance or resistivity and is a characteristic of the material of the wire.
Observations
Range of ammeters = _____ mA to _____ mA
The Least count of ammeter = _____ mA
Range of voltmeter = _____ V to ____ V
The Least count of voltmeter = _____ V
The Least count of meter-scale = _____ m
Length of the given wire, l = _____ m
S. No The applied potential difference Current flowing through the wire
(voltmeter reading V) (Milliammeter Reading A)
Calculations
1. Plot a graph between the potential difference across the wire V and the current I flowing
through the wire
2. Determine the slope of the graph. The resistance of the given wire is then equal to the
Reciprocal of the slope. From the graph, R = BC/AB = _____ Ω
3. Resistance per unit length of the wire = R/t = _____ Ωm–1
Result
The potential difference across the wire varies linearly with the current.
The resistance per unit length of the wire is ( R ± ΔR) = _____ ± _____ Ωm–1).
, Experiment – 2
Aim
To find resistance of a given wire using metre bridge and hence determine the resistivity (specific resistance) of
its material.
Materials Required
1. A metre bridge
2. A Leclanche cell (battery eliminator)
3. A galvanometer
4. A resistance box
5. A jockey
6. A one-way key
7. A resistance wire
8. A screw gauge
9. A metre scale
10. A set square
11. Connecting wires
12. A piece of sandpaper
Theory
Metre bridge apparatus is also known as a slide wire bridge. It is fixed on the wooden block and consists of a
long wire with a uniform cross-sectional area. It has two gaps formed using thick metal strips to make
theWheatstone’s bridge.
Then according to Wheatstone’s principle, we have:
XR=l / (100−l)
The unknown resistance can be calculated as:
X=Rl / (100−l)
Then the specific resistance of the material of the is calculated as:
ρ=πr2 X / L
Where,
L is the length of the wire
r is the radius of the wire
Exp. No Aim
Section – A
1 To determine resistivity of two / three wires by plotting a graph for potential
difference versus current.
2 To find resistance of a given wire / standard resistor using metre bridge
3 To compare the EMF of two given primary cells using potentiometer.
4 To determine resistance of a galvanometer by half-deflection method and to
find its figure of merit
Section - B
5 To find the focal length of a convex lens by plotting graphs between u and v or
between 1/u and 1/v.
6 To find the focal length of a convex mirror, using a convex lens.
7 To determine angle of minimum deviation for a given prism by plotting a
graph between angle of incidence and angle of deviation.
8 To draw the I-V characteristic curve for a p-n junction diode in forward bias
and reverse bias.
Activities
1 To measure resistance, voltage (AC/DC), current (AC) and check continuity of
a given circuit using multimeter.
2 To assemble a household circuit comprising three bulbs, three (on/off)
switches, a fuse and a power source
3 To assemble the components of a given electrical circuit
4 To identify a diode, an LED, a resistor and a capacitor from a mixed collection
of such items.
5 To observe polarization of light using two Polaroids
6 To observe diffraction of light due to a thin slit
, Experiment – 1
Aim
To determine the resistance per cm of a given wire by plotting a graph for potential difference versus
current.
Apparatus/ Material Required
A wire of unknown resistance
Battery
Voltmeter
Milliammeter
Rheostat
Plug key
Connecting wires
Piece of sandpaper
Circuit Diagram
,Theory
According to Ohm’s law, the electric current flowing through a conductor is directly proportional to the potential
difference across its ends, provided the physical state (pressure, temperature, and dimensions) of the conductor
remains unchanged.
If I is the current flowing through the conductor and V is the potential difference across its end, then
V∝I
and hence
V = RI
Where R is the constant of proportionality and is termed as the electrical resistance of the conductor.
ResistanceR depends on the dimensions and material of the conductor. The relationship between the resistance
of a material and its length and area of the cross-section is given by the formula
R=ρ / A’
Where ρ is the specific resistance or resistivity and is a characteristic of the material of the wire.
Observations
Range of ammeters = _____ mA to _____ mA
The Least count of ammeter = _____ mA
Range of voltmeter = _____ V to ____ V
The Least count of voltmeter = _____ V
The Least count of meter-scale = _____ m
Length of the given wire, l = _____ m
S. No The applied potential difference Current flowing through the wire
(voltmeter reading V) (Milliammeter Reading A)
Calculations
1. Plot a graph between the potential difference across the wire V and the current I flowing
through the wire
2. Determine the slope of the graph. The resistance of the given wire is then equal to the
Reciprocal of the slope. From the graph, R = BC/AB = _____ Ω
3. Resistance per unit length of the wire = R/t = _____ Ωm–1
Result
The potential difference across the wire varies linearly with the current.
The resistance per unit length of the wire is ( R ± ΔR) = _____ ± _____ Ωm–1).
, Experiment – 2
Aim
To find resistance of a given wire using metre bridge and hence determine the resistivity (specific resistance) of
its material.
Materials Required
1. A metre bridge
2. A Leclanche cell (battery eliminator)
3. A galvanometer
4. A resistance box
5. A jockey
6. A one-way key
7. A resistance wire
8. A screw gauge
9. A metre scale
10. A set square
11. Connecting wires
12. A piece of sandpaper
Theory
Metre bridge apparatus is also known as a slide wire bridge. It is fixed on the wooden block and consists of a
long wire with a uniform cross-sectional area. It has two gaps formed using thick metal strips to make
theWheatstone’s bridge.
Then according to Wheatstone’s principle, we have:
XR=l / (100−l)
The unknown resistance can be calculated as:
X=Rl / (100−l)
Then the specific resistance of the material of the is calculated as:
ρ=πr2 X / L
Where,
L is the length of the wire
r is the radius of the wire
