A copper wire has a diameter of 0.5 mm and resistivity of 1.6 × 10–8Ω m. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?

How is a voltmeter connected in the circuit to measure the potential difference between two points?

Two conducting wires of the same material and equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be : (a) 1 : 2 (b) 2 : 1 (c) 1 : 4 (d) 4 : 1

Which of the following terms does not represent electrical power in a circuit? (a) I2R (b) IR2 (c) VI (d) V2/R [NCERT]

A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R’, then the ratio R/R’ is : (a) 1/25 (b) 1/5 (c) 5 (d) 25

An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h