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Question 3
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If the internal resistance of the battery is
0
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4 Ω
Maximum current drawn from the battery = I
According to Ohm’s law,

The maximum current drawn from the given battery is 30 A
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2:
A battery of emf 10 V and internal resistance 3 Ω is connected
connected to a resistor
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5 A, what is the resistance of the resistor? What is the terminal voltage
of the battery when the circuit is closed?
Answer

Emf of the battery, E = 10 V
Internal resistance of the battery, r = 3 Ω

Current in the circuit, I = 0
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5 × 17
= 8
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5 V
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3:
Three resistors 1 Ω, 2 Ω, and 3 Ω are combined in series
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Answer

Three resistors of resistances 1 Ω, 2 Ω, and 3 Ω are combined in series
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Total resistance = 1 + 2 + 3 = 6 Ω
Current flowing through the circuit = I
Emf of the battery, E = 12 V
Total resistance of the circuit, R = 6 Ω
The relation for current using Ohm’s law is,

Potential drop across 1 Ω resistor = V1
From Ohm’s law, the value of V1 can be obtained as
V1 = 2 × 1= 2 V … (i)
Potential drop across 2 Ω resistor = V2
Again, from Ohm’s law, the value of V2 can be obtained as
V2 = 2 × 2= 4 V … (ii)
Potential drop across 3 Ω resistor = V3
Again, from Ohm’s law, the value of V3 can be obtained as
V3 = 2 × 3= 6 V … (iii)
Therefore, the potential drop across 1 Ω, 2 Ω, and 3 Ω resistors are 2 V, 4 V, and 6 V
respectively
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4:
Three resistors 2 Ω, 4 Ω and 5 Ω are combined in parallel
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Answer

There are three resistors of resistances,
R1 = 2 Ω, R2 = 4 Ω, and R3 = 5 Ω
They are connected in parallel
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Therefore, the current through each resister is 10 A, 5 A, and 4 A respectively and the
total current is 19 A
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5:
At room temperature (27
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What is the
temperature of the element if the resistance is found to be 117 Ω, given that the
temperature coefficient of the material of the resistor is
Answer

Room temperature, T = 27°C
Resistance of the heating element at T, R = 100 Ω
Let T1 is the increased temperature of the filament
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Question 3
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0 × 10−7 m2, and its resistance is measured to be 5
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What is the resistivity of
the material at the temperature of the experiment?
Answer

Length of the wire, l =15 m
Area of cross-section
section of the wire, a = 6
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0 Ω
Resistivity of the material of the wire = ρ
Resistance is related with the resistivity as

Therefore, the resistivity of the material is 2 × 10−7 Ω m
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7:
A silver wire has a resistance of 2
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5 °C, and a resistance of 2
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Determine the temperature coefficient of resistivity of silver
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5°C
Resistance of the silver wire at T1, R1 = 2
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7 Ω
Temperature coefficient of silver = α
It is related with temperature and resistance as

Therefore, the temperature coefficient of silver is 0
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Question 3
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2 A which settles after a few seconds toa steady value of 2
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What is the steady
temperature of the heating element if the room temperature is 27
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70 × 10−4 °C −1
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2 A
Initial resistance = R1, which is given by the relation,

Steady state value of the current, I2 = 2
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70 × 10−4 °C −1
Initial temperature of nichrome, T1= 27
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5°C

Question 3
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30:

Answer

Current flowing through various branches of the circuit is represented in the given figure
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e
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e
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e
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10:
In a metre bridge [Fig
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27], the balance point is found to be at 39
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5 Ω
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Why are the connections
between resistors in a Wheatstone or meter bridge made of thick copper strip
strips?
Determine the balance point of the bridge above if X and Y are interchanged
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Balance point from end A, l1 = 39
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5 Ω
Condition for the balance is given as,

Therefore, the resistance of resistor X is 8
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The connection between resistors in a Wheatstone or metre bridge is made of thick copper
strips to minimize the resistance, which is not taken into consideration in the bridge
formula
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The balance point of the bridge will be 100−l1 from A
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5 =

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