Physics Experiments Cycle 1 Grade 12 (2022-23)
Physics Experiments Cycle 1 Grade 12 (2022-23)
Physics Experiments Cycle 1 Grade 12 (2022-23)
PHYSICS EXPERIMENTS
GRADE 12 : 2022-23
SECTION A – CYCLE 1
S.NO EXPERIMENTS
1. To determine resistivity of two wires by plotting a graph for potential difference versus
current.
EXPERIMENT 1
AIM
To determine resistivity of two wires by plotting a graph for potential difference versus current.
APPARATUS
Two resistance wires, a voltmeter and an ammeter of appropriate range, a battery eliminator, a
rheostat, a metre scale, one way key, connecting wires and a piece of sand paper.
THEORY
According to the Ohm’s law, the current through a conductor is directly proportional to the
applied voltage, provided temperature and other physical conditions of the conductor remain
unchanged.
VαI
V = IR, where R is the resistance of the conductor.
𝑅𝐴
Reisitivity ρ = , where A is the area of cross-section and l is the length of the wire.
𝑙
Model Graph
Procedure
1. Arrange the apparatus in the same manner as given in the arrangement diagram.
2. Determine the least count of voltmeter and ammeter
3. Insert the key K, slide the rheostat contact and see that ammeter and voltmeter are
working properly.
4. Adjust the sliding contact of the rheostat such that a measurable current passes through
the resistance coil or the resistance wire.
5. Note down the value of potential difference V” from voltmeter and current I from
ammeter
6. Shift the rheostat contact slightly and take readings on both ammeter and voltmeter
7. Take at least six sets of independent observations
8. Plot a graph between V along X axis and I along Y-axis. Find V/I by taking slope
between two points in the graph and find the resistance of first wire.
9. Note the area of cross section of the wire
10. Find the resistivity of the first wire using the formula.
11. Repeat the experiment for the second wire and find the resistivity of the second wire.
OBSERVATIONS
Least count of voltmeter=
Least count of ammeter =
Wire-1
Wire-2
Calculation:
Area of cross section the wire 1=
Resistance of the wire 1= 1/slope =
Length of the wire 1=
𝑅𝐴
Resistivity of the wire 1, ρ = 𝑙 ,
Result
Resistivity of the wire-1=
Resistivity of the wire-2=
Precautions
Sources of error
EXPERIMENT 2
Aim
To find resistance of a given wire using Metre Bridge.
Apparatus
A meter bridge, galvanometer, one way key, a resistance box, a battery, jockey, unknown
resistance wire about 1m long and connecting wire.
Theory
The unknown resistance X is given by
where, R is known resistance placed in the left gap and I (in cm) is the length of metre bridge
wire from zero end upto balance point.
Procedure
Observation table
Mean X = Ω
Result
Precautions
EXPERIMENT 3
Aim
To determine the resistance of a galvanometer by half-deflection method and to find its figure of
merit.
Apparatus
A galvanometer, a voltmeter, a battery or battery eliminator, two (10,000 Ω and 200 Ω)
resistance boxes, two one-way keys, a rheostat, a screw gauge, a metre scale, an ammeter of
given range, connecting wires and a piece of sand paper.
Circuit Diagram
Procedure
Observation table
Calculations:
Mean G = Ω
Figure of merit =
Result
Resistance of the given galvanometer=
Figure of merit of the galvanometer =
Precautions
Sources of error
EXPERIMENT 4
Aim
To find the frequency of the AC mains with a sonometer.
Apparatus
A sonometer (with soft iron wire), ½ kg hanger, seven ½ kg slotted weights, an electromagnet
with a step-down transformer, clamp stand, rubber pad, metre scale.
Theory
1 √𝑻
Frequency of ac mains using sonometer ,𝜐 = , where l is the resonance length, T the
4 √𝑚 𝒍
tension in the string and m is the mass per unit length of the wire.
Procedure
1. Place the sonometer on the table such that pulley projects beyond the edge of the table.
Put suitable weight on the hanger.
2. Move the bridges to outward position so that maximum length can be accommodated.
3. Clamp the electromagnet in a stand keeping one of its core very close to the middle of the
sonometer wire.
4. Switch on the electromagnet and adjust the length of vibrating wire by moving knife
edges with small length until the wire begins to vibrate.
5. Now make minor adjustments to make the amplitude of the vibrating wire maximum, in
that case we will hear a hissing sound in wire.
6. Note the load on the wire and measure the length of the vibrating portion of wire in both
length increasing and decreasing i.e l1 and l2
7. Now change the load of the hanger and repeat the same procedure to obtain resonating
length of the wire. Take 5 sets of such readings.
Observation
Linear density of the wire, m = kgm -1
Observation table
Tension Resonant Length
√𝑻
S.NO Length Length Mean
T=mg l1 l2 l= (l1+l2)/2 𝒍
(in N) N1/2m-1
Increasing Decreasing (m)
√𝑻
Mean = N1/2m-1
𝒍
1 √𝑻
𝜐= =
4 √𝑚 𝒍
Result
The frequency of alternating current = Hz
Precautions
Sources of error