Question

II. Questions of 2 Marks
1) The electrical resistivities of four materials P,Q,R & S are given below
P= 6.84 x 10-8 92m
Q = 1.70 x 10-8 Nm
R = 1.0 x 1015 m
S = 11.0 x 10-7 Nm
Which material will you use for making
a) Heating element of electric iron
b) Connecting wire of electric iron
c) Covering of connecting wires​

Answer 1

Explanation:

(a) S; because it has high resistivity of 11 X 10-7ohm-m (it is actually nichrome).

(b) Q; because it has very low resistivity of 1.7 X 10-8ohm-m (it is actually copper).

(c) R; because it has very very high resistivity of 1.0 X 1015ohm-m (it is actually rubber).