- 1(current)
Q. No.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.
In the given figure each plate of capacitance C has partial value of charge equal to:
1. CE
2.
3.
4.
A 4 μF capacitor and a resistance of 2.5 MΩ are in series with a 12 V battery. The time after which the potential difference across the capacitor is 3 times the potential difference across the resistor is: [Given ln(2)= 0.693]
1. 13.86 s
2. 6.93 s
3. 7 s
4. 14 s
In the figure below, what is the potential difference between the point A and B and between B and C, respectively, in steady state?
1.
2.
3.
4.
When the key K is pressed at time t = 0, which of the following statement about the current I in the resistor AB of the given circuit is true?
| 1. | I = 2 mA at all t |
| 2. | I oscillates between 1 mA and 2 mA |
| 3. | I = 1 mA at all t |
| 4. | At t = 0 , I = 2 mA and with time, it goes to 1 mA |
A capacitor of 4 is connected as shown in the circuit. The internal resistance of the battery is 0.5 . The amount of charge on the capacitor plates will be:
1. 0
2. 4
3. 16
4. 8
Consider a capacitor-charging circuit. Let Q1 be the charge given to the capacitor in a time interval of 10 ms and Q2 be the charge given in the next time interval of 10 ms. Let 10 µC charge be deposited in a time interval J, and the next 10 µC charge is deposited in the next time interval t2
1. Q1 > Q2 , t1 > t2
2. Q1 > Q2 , t1 < t2
3. Q1 < Q2 , t1 > t2
4. Q1 < Q2 , t1 < t2
(a) The current in each of the two discharging circuits is zero at t = 0.
(b) The currents in the two discharging circuits at t = 0 are equal but not zero.
(c) The currents in the two discharging circuits at t = 0 are unequal.
(d) C1 loses 50% of its initial charge sooner than C2 loses 50% of its initial charge
Choose the correct option
1. (a) only
2. (b), (d)
3. (c), (d)
4. (a), (d)
A battery of emf E is used to charge an uncharged capacitor C, through a resistance R. The time constant of the circuit is \({\tau = RC}\).
| Assertion (A): | When the voltage across the capacitor reaches 50% of its maximum value, the rate of heat dissipation in the resistor falls to \(\frac14\) of its initial value. |
| Reason (R): | The voltage across the capacitor is proportional to the charge on its plates, while the rate of flow of charge is the current (i). This current (i) falls exponentially with a time constant T, and it falls to 50% of its initial value when the capacitor is 50% charged. The rate of heat dissipation, being proportional to i2, falls to \(\frac14\) of its initial value. |
In the light of the above statements choose the correct answer from the options given below:
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | (A) is false but (R) is true. |
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Q. No.
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