# Electrical Engineering Questions and Answers

### 1. A kilowatt hour is the unit of

(i) energy
(ii) power
(iii) electric charge
(iv) electric current

### 2. Heat produced in a conductor depends

(i) inversely on time
(ii) directly on time
(iii) both (i) and (ii)
(iv) none of the above

(i) ρ
(ii) ρ2
(iii) 1/√ρ
(iv) 1/ρ

(i) 36 x 103J
(ii) 103J
(iii) 36 x 105 J
(iv) 105 J

(i) nichrome
(ii) iron
(iii) tungsten
(iv) constantan

(i) 0.25 A
(ii) 3/10 A
(iii) 2.5 A
(iv) 10/3 A

### 7. Three electric bulbs 40 W, 60 W and 100 W are designed to work on a 220 V mains. Which bulb will burn most brightly if they are connected in series across 220 V mains?

(i) 60 W
(ii) 40 W
(iii) 100 W
(iv) all bulbs will bum equally brightly

### 8. Two electric bulbs have tungsten filament of the same length. If one of them gives 60 W and the other 100 W, then,

(i) 100 W bulb has thicker filament
(ii) 60 W bulb has thicker filament
(iii) both filaments are of the same thickness
(iv) information insufficient

(i) 20 W
(iii) 80 W
(ii) 60 W
(iv) 100 W

(i) 210 sec
(ii) 840 sec
(iii) 42 sec
(iv) 420 sec

(i) 80 W
(ii) 20 W
(iii) 160 W
(iv) 40 W

### 12. Two bulbs, 100 W, 250 V and 200 W, 250 V, am connected in parallel across a 500 V line. Then,

(i) 100 W bulb will be fused
(ii) 200 W bulb will be fused
(iii) Both bulbs will be fused
(iv) No bulb will be fused

### 13. Two bulbs, 100 W, 250 V and 200 W, 250 V are connected in series to a 500 V line. Then,

(i) 100 W bulb will be fused
(ii) 200 W bulb will be fused
(iii) both bulbs will be fused
(iv) no bulb will be fused

(i) decrease
(i) increase
(iii) No change
(iv) cannot say

### 15. You are given the following electrical appliances (a) 1 kW, 250 V electric heater (b) 1 kW, 250 V, electric kettle (c)1 kW, 250 V, electric bulb. Which of these has the highest resistance ?

(i) heater
(ii) kettle
(iii) bulb
(iv) all have equal resistances

(i) 2%
(ii) 4 %
(iii) 1 %
(iv) 16%

(i) 5 : 3
(ii) 9 : 25
(iii) 3 : 5
(iv) 25 : 9

(i) 81 : 1
(ii) 1 : 81
(iii) 3 : 1
(iv) 9 : 1

(i) 484 W
(ii) 672 W
(iii) 526 W
(iv) 620 W

(i) half
(ii) twice
(iii) one-fourth
(iv) same