# NCERT Class X Science Solutions: Chapter 12 – Electricity Part 2 (For CBSE, ICSE, IAS, NET, NRA 2022)

Doorsteptutor material for CBSE/Class-10 Science is prepared by world's top subject experts: fully solved questions with step-by-step explanation- practice your way to success.

Question 4:

Two conducting wires of the same material and of 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

Heat produced in the circuit is inversely proportional to the resistance R. Let and be the equivalent resistances of the wires if connected in series and parallel respectively. Let R be the resistance of each wire.

If the resistors are connected in parallel, the net resistance is given by

If the resistors are connected in series, the net resistance is given by

Hence, for same potential difference V, the ratio of heat produced in the circuit is given by

Therefore, the ratio of heat produced in series and parallel combinations is

Hence, the option C is correct.

Question 5:

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

To measure the potential difference, a voltmeter should be connected in parallel.

A voltmeter is a device that measures potential difference.

The voltmeter must be connected in parallel with the elements being measured.

Question 6:

A copper wire has diameter and resistivity of what will be the length of this wire to make its resistance how much does the resistance change if the diameter is doubled?

Resistance of a copper wire of length and cross-section is given by the expression,

Where, ρ is resistivity of copper