List of top Physics Questions on Power in Electric Circuits

In the circuit given below, identify the lamp (L1, L2, L3 or L4) whose failure would not interrupt the power supply to the other lamps.
The correct formula to calculate the equivalent resistance of R\(_1\) and R\(_2\) when connected in parallel, is:
An electric iron rated 1100 W, 220 V is operated for 5 hours.
Calculate:
(a) the minimum rating of the fuse required.
(b) the energy consumed in kWh.
(c) the cost of the energy consumed, if the rate is Rupees 10 per unit.
In the combinations of resistors shown below, calculate:
(a) the resistance across AB when the switch S is open.
(b) the resistance across AB when the switch S is closed.
Bulb A rated 160 W, 40 V and Bulb B rated 40 W, 40 V are connected as shown in the diagram.
(a) Calculate the ratio V\(_1\) : V\(_2\)
(b) If the bulb A fuses, the current in the circuit remains the same. State True or False.
A resistance R is connected across a cell with a switch and a rheostat in series. A voltmeter is connected parallel across the cell. Current in the circuit is increased using the rheostat.
(a) How will the voltmeter reading change? (increase / decrease / remain the same)
(b) Justify your answer stated in (a) above.
A straight wire of resistance $18~\Omega$ is bent in the form of an equilateral triangle. The effective resistance between any two vertices of the triangle is
A wire of resistance \( R \) is bent in the form of a circular loop. Two points on the circle separated by a quarter circumference are connected to a battery of emf \( E \) and negligible internal resistance. The heat generated in the wire per second is:
In a meter bridge, the null point is located at 20 cm from the left end of the wire when resistances \( R \) and \( S \) are connected in the left and right gaps respectively. If the resistance \( S \) is shunted with \( 60\,\Omega \) resistance, the null point shifted by 5 cm, then the values of \( R \) and \( S \) are respectively:
If current of 80 A is passing through a straight conductor of length 10 m, then the total momentum of electrons in the conductor is (mass of electron \( = 9.1 \times 10^{-31} \) kg and charge of electron \( = 1.6 \times 10^{-19} \) C)
The readings of the voltmeter and ammeter in the circuit shown in the diagram are respectively
readings of the voltmeter and ammeter
The length and area of cross-section of a copper wire are respectively 30 m and \( 6 \times 10^{-7} \, \text{m}^2 \). If the resistivity of copper is \( 1.7 \times 10^{-8} \, \Omega \, \text{m} \), then the resistance of the wire is
A wire of resistance \( R \) is bent in the form of a circular loop. Two points on the circle separated by a quarter circumference are connected to a battery of emf \( E \) and negligible internal resistance. The heat generated in the wire per second is:
When two identical batteries of internal resistance 1 Ω each are connected in series across a resistor R, the rate of heat produced in R is P1. When the same batteries are connected in parallel across R, the rate of heat produced is P2. If P1 = 2P2, then the value of R is
In a potentiometer experiment, when two cells of emfs \( E_1 \) and \( E_2 \) (\( E_2>E_1 \)) are connected in series, the balancing length is 160 cm. If one of the cells is reversed, the balancing length decreases by 75%. If \( E_1 = 1.2 \, V \), then \( E_2 \) is
When a wire is connected in the left gap of a metre bridge, the balancing point is at \( 40 \) cm from the left end of the bridge wire. If the wire in the left gap is stretched so that its length is doubled and again connected in the same gap, then the balancing point from the left end of the bridge wire is:

If each resistance in the given figure is 9 $\Omega$, then the reading of the ammeter (A) is

The power dissipated by a uniform wire of resistance $100~\Omega$ when a potential difference of $120~\text{V$ is applied across its ends is}
Two batteries of emfs 3V and 6V and internal resistances 0.2 and 0.4 are connected in parallel. This combination is connected to a 4 resistor. Find:
(i) the equivalent emf of the combination
(ii) the equivalent internal resistance of the combination
(iii) the current drawn from the combination
If a wire of length \( L \) carrying a current \( i \) is bent in the shape of a semi-circular arc as shown in the figure, then the magnetic field at the centre of the arc is:
When a wire is connected in the left gap of a metre bridge, the balancing point is at \( 40 \) cm from the left end of the bridge wire. If the wire in the left gap is stretched so that its length is doubled and again connected in the same gap, then the balancing point from the left end of the bridge wire is:
The length and area of cross-section of a copper wire are respectively 30 m and \( 6 \times 10^{-7} \, \text{m}^2 \). If the resistivity of copper is \( 1.7 \times 10^{-8} \, \Omega \, \text{m} \), then the resistance of the wire is
If current of 80 A is passing through a straight conductor of length 10 m, then the total momentum of electrons in the conductor is (mass of electron \( = 9.1 \times 10^{-31} \) kg and charge of electron \( = 1.6 \times 10^{-19} \) C)
A wire of resistance 100 \(\Omega\) is stretched so that its length increases by 20%. The stretched wire is then bent in the form of a rectangle whose length and breadth are in the ratio 3 : 2. The effective resistance between the ends of any diagonal of the rectangle is

In the following diagram, the work done in moving a point charge from point P to point A, B and C are \( W_A, W_B, W_C \) respectively. Then (A, B, C are points on semicircle and point charge \( q \) is at the centre of semicircle)