A light bulb, a capacitor and a battery are connected together as shown below with the switch S initially open. When the switch S is closed, which one of the following is true?
1. The bulb will light up for an instant when
the capacitor starts charging.
2. The bulb will light up when
the capacitor is fully charged.
3. The bulb will not light up at all.
4. The bulb will light up and go off at regular intervals.
A filament bulb (500 W,100 V) is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R is
1. 230
2. 46
3. 26
4. 13
The circuit shown here is used to compare the e.m.f. of two cells and . The null point is at C when the galvanometer is connected to E1. When the galvanometer is connected to E2, the null point will be
1. To the left of C
2. To the right of C
3. At C itself
4. Nowhere on AB
In the diagram shown, the reading of voltmeter is 20 V and that of ammeter is 4 A. The value of R should be (consider given ammeter and voltmeter are not ideal) :
1. Equal to 5 Ω
2. Greater from 5 Ω
3. Less than 5 Ω
4. Greater or less than 5 Ω depends on the material of R
Two cells when connected in series are balanced on 8m on a potentiometer. If the cells are connected with polarities of one of the cells reversed, they balance on 2m. The ratio of e.m.f.'s of the two cells is
1. 3 : 5
2. 5 : 3
3. 3 : 4
4. 4 : 3
A potentiometer is used for the comparison of e.m.f. of two cells E1 and E2. For cell E1 the no deflection point is obtained at 20cm and for E2 the no deflection point is obtained at 30cm. The ratio of their e.m.f.'s will be
1. 2/3
2. 1/2
3. 1
4. 2
A galvanometer can be used as a voltmeter by connecting a :
1. High resistance in series
2. Low resistance in series
3. High resistance in parallel
4. Low resistance in parallel
In order to pass 10% of the main current through a moving coil galvanometer of 99 ohms, the resistance of the required shunt is :
1. 9.9 Ω
2. 10 Ω
3. 11 Ω
4. 9 Ω
For measurement of potential difference, the potentiometer is preferred in comparison to the voltmeter because:
1. the potentiometer is more sensitive than the voltmeter.
2. the resistance of the potentiometer is less than
the voltmeter.
3. the potentiometer is cheaper than the voltmeter.
4. the potentiometer does not take current from the circuit.
The figure below shows currents in a part of electric circuit. The current i is
1. 1.7 amp
2. 3.7 amp
3. 1.3 amp
4. 1 amp