Which of the following materials has an increase in resistance with temperature?
water
metals
wood
electrolyte
Correct answer is B
Resistance in metals are proportional to temperature
600 J
50 J
133 J
250 J
Correct answer is A
Inductance (L) in series: 4 + 8 = 12
Therefore Energy stored =
W = \(\frac{1}{2} LI^2\)
= \(\frac{1}{2} \times 12 \times 10^2\)
= 600J
Under which of the following conditions do gases conduct electricity?
Low presssure and low p.d
low pressure and high p.d
high pressure an low p.d
high pressure and high p.d
Correct answer is B
Under high potential difference and low pressure gases are good conductor of electricity
N28
N12
N16
N24
Correct answer is B
Energy consumed = power x time = lvt = 2 x 250 x 6hr = 300 wh = 3 kwh but 1 kwh = N4
3 kwh = 3 x N4 = N 12
In measuring high frequency a.c, the instrument used is the
d.c ammeter
moving coil ammeter
moving iron ammeter
hot wire ammeter
Correct answer is D
Hot wire ammeter is used because the heat affect of A C is same as that of DC