$(a)$ Define potential difference between two points in a conductor.
$(b)$ Name the instrument used to measure the potential difference in a circuit. How is it connected ?
$(c)$ A current of $2\, A$ passes through a circuit for $1$ minute. If potential difference between the terminals of the circuit is $3 \,V,$ what is the work done in transferring the charges ?
$(a)$ Electric potential difference between two points in an electric circuit carrying current is the work done to move a unit charge from one point to the other.
$(b)$ Voltmeter. It is connected in parallel.
$(c)$ $I=2 A, t=1 \text { minute }=60 s, V=3 V$
$Q = I t=2 \times 60=120 C$
Therefore, $W=V Q=3 \times 120=360 J$
A current of $1$ ampere flows in a series circuit containing an electric lamp and a conductor of $5\,\Omega $ when connected to a $10\, V$ battery. Calculate the resistance of the electric lamp.
Now if a resistance of $10\,\Omega $ is connected in parallel with this series combination, what change (if any) in current flowing through $5\,\Omega $ conductor and potential difference across the lamp will take place? Give reason.
A nichrome wire has a resistance of $10\, \Omega$. Find the resistance of another nichrome wire, whose length is three times and area of cross-section four times the first wire.
The following table gives the resistivity of three samples
Sample | $A$ | $B$ | $C$ |
Resistivity | $1.6 \times 10^{-8} \Omega m$ | $5.2 \times 10^{-8} \Omega m$ | $100 \times 10^{-6} \Omega m$ |
Which of them is suitable for heating elements of electrical appliances and why ?
Resistance of a conductor increases with the increase in temperature.
If a wire of resistance $R$ is melted and recast to half of its length, then new resistance of the wire will be