CBSE - Class 12 Physics Current Electricity Worksheet
1.
The storage battery of a car has an emf of 12 V. If the internal resistance of the battery is $0.4 \Omega$, what is the maximum current that can be drawn from the battery?
2.
A heating element using nichrome connected to a 230 V supply draws an initial current of 3.2 A which settles after a few seconds to a steady value of 2.8 A. What is the steady temperature of the heating element if the room temperature is 27.0 °C? Temperature coefficient of resistance of nichrome averaged over the temperature range involved is $1.70 \times 10^{-4} °C^{-1}$.
3.
A silver wire has a resistance of $2.1 \Omega$ at 27.5 °C, and a resistance of $2.7 \Omega$ at 100 °C. Determine the temperature coefficient of resistivity of silver.
4.
At room temperature (27.0 °C) the resistance of a heating element is $100 \Omega$. What is the temperature of the element if the resistance is found to be $117 \Omega$, given that the temperature coefficient of the material of the resistor is $1.70 \times 10^{-4} °C^{-1}$.
5.
A negligibly small current is passed through a wire of length 15 m and uniform cross-section $6.0 \times 10^{-7} m^2$, and its resistance is measured to be $5.0 \Omega$. What is the resistivity of the material at the temperature of the experiment?
6.
A storage battery of emf 8.0 V and internal resistance $0.5 \Omega$ is being charged by a 120 V dc supply using a series resistor of $15.5 \Omega$. What is the terminal voltage of the battery during charging? What is the purpose of having a series resistor in the charging circuit?
7.
Determine the current in each branch of the network shown in Fig. 3.20:
8.
The number density of free electrons in a copper conductor estimated in Example 3.1 is $8.5 \times 10^{28} m^{-3}$. How long does an electron take to drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is $2.0 \times 10^{-6} m^2$ and it is carrying a current of 3.0 A.
9.
A battery of emf 10 V and internal resistance $3 \Omega$ is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed?
