In the circuit shown in the figure, if potential at point A is taken to be zero, the potential at point B is

–1V
+ 2V
–2V
+ 1V

Solution

In producing chlorine by electrolysis 100 kW power at 125V is being consumed. How much chlorine per minute is liberated?(E.C.E. of chlorine is 0.367×10^–6 kg /C)

1.76× 10^–3kg
9.67 × 10^–3kg
17.61 × 10^–3kg
3.67 × 10^–3kg

Solution

For the network shown in the figure the value of the currenti is

^9V⁄₃₅
^18V⁄₅
^5V⁄₉
^5V⁄₁₈

Solution

In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb foruse in USA will be

Solution

When three identical bulbs of 60 watt, 200 volt rating are connected in series to a 200 volt supply, the power drawn by them will be

20 watt
60 watt
180 watt
10 watt

Solution

A battery is charged at a potential of 15 V for 8 hours when the current flowing is 10A. The battery on discharge supplies acurrent of 5A for 15 hour. The mean terminal voltage during discharge is 14V. The “Watt-hour”efficiency of the battery is

87.5%
82.5%
80%
90%

Solution

Five equal resistances each of resistance R are connected as shown in the figure. A battery of V volts is connected between A and B. The current flowing in AFCEB will be

^2V⁄_R
^2V⁄_R
^V⁄_R
^V⁄_2R

Solution

A balanced Wheatstone’s bridge exists between A & B. R_eq = R

current through circuit is V/R

current through AFCEB= V/2R

The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then

the resistance and the specific resistance, will both remain unchanged
the resistance will be doubled and the specific resistance will be halved
the resistance will be halved and the specific resistance will remain unchanged
the resistance will be halved and the specific resistance will be doubled

Solution

Two 220 volt,100 watt bulbs are connected first in series and then in parallel.Each time the combination is connected to a 220 volt a.c. supply line. The power drawn by the combination in each case respectively will be

50 watt,200 watt
50 watt, 100 watt
100 watt, 50 watt
200 watt, 150 watt

Solution

\(Power\frac{1}{Resistance}\)

In series combination, Resistance doubles Hence, Power will be halved.In parallel combination, resistance halved Hence, power will be double.

An electric kettle has two heating coils. When one of the coils is connected to an a.c. source, the water in the kettle boils in 10 minutes. When the other coil is used the water boils in 40 minutes. If both the coils are connected in parallel,the time taken by the same quantity of water to boil will be

15 min
8 min
4 min
25 min

Solution

Time = \(\frac{10\times 40}{10+40}=\frac{400}{50}=8\)

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