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(a) Name a device which is used to :
(i) Maintain a constant potential difference in a circuit.
(ii) Change the electric current in an electric circuit.
(b) When the potential difference between the terminals of an electric heater is $$\begin{aligned}& 110 \\ & \text{V}\end{aligned}$$, a current of $$\begin{aligned}& 5 \\ & \text{A}\end{aligned}$$ flows through it. What will be the value of current flowing through it when the potential difference is increased to $$\begin{aligned}& 220 \\ & \text{V}\end{aligned}$$ ?
(i) Maintain a constant potential difference in a circuit.
(ii) Change the electric current in an electric circuit.
(b) When the potential difference between the terminals of an electric heater is $$\begin{aligned}& 110 \\ & \text{V}\end{aligned}$$, a current of $$\begin{aligned}& 5 \\ & \text{A}\end{aligned}$$ flows through it. What will be the value of current flowing through it when the potential difference is increased to $$\begin{aligned}& 220 \\ & \text{V}\end{aligned}$$ ?
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(a) (i) Battery / Electric cell
(ii) Rheostat / Variable resistance
(b) Resistance of the heater, $R = \frac{V}{I} = \frac{110}{5} = 22 \Omega$
Current through the heater, $I' = \frac{V'}{R} = \frac{220}{22} = 10 A$
Alternate answer for (b):
• According to Ohm's law, potential difference is directly proportional to current.
• When the potential difference is doubled, current will also be doubled. So, value of current will be 10A.
(ii) Rheostat / Variable resistance
(b) Resistance of the heater, $R = \frac{V}{I} = \frac{110}{5} = 22 \Omega$
Current through the heater, $I' = \frac{V'}{R} = \frac{220}{22} = 10 A$
Alternate answer for (b):
• According to Ohm's law, potential difference is directly proportional to current.
• When the potential difference is doubled, current will also be doubled. So, value of current will be 10A.