Two identical parallel plate air capacitors are connected in series to a battery of e.m.f. . If one of the capacitor is completely filled with dielectric material of constant , then potential difference of the other capacitor will become
1
2
3
4
Official Solution
Correct Option: (2)
Let the capacitance of capacitor be . Thus capacitance of capacitor is . Potential across the capacitor
02
PYQ 2020
medium
physicsID: mht-cet-
In the figure shown, the voltage across will be:
1
2
3
4
Official Solution
Correct Option: (4)
Step 1: Understanding the Capacitor Circuit. In this circuit, capacitors and are in series and their equivalent capacitance is:
This series combination is in parallel with . The total equivalent capacitance of the circuit is:
Step 2: Voltage Across . The voltage across is given by the voltage division rule:
Step 3: Final Answer. Thus, the voltage across is .
03
PYQ 2020
medium
physicsID: mht-cet-
In suspended type of moving coil galvanometer
1
coil is stationary.
2
magnet is stationary.
3
magnet and coil are stationary.
4
magnet and coil are moving.
Official Solution
Correct Option: (2)
Step 1: Structure of suspended type galvanometer. In a suspended type moving coil galvanometer, the coil is suspended by a thin fibre and is free to rotate when current flows through it.
Step 2: Role of magnet. The permanent magnet provides a strong radial magnetic field and remains fixed in position.
Step 3: Deflection mechanism. When current passes through the suspended coil, it experiences a torque and rotates, producing deflection. The magnet itself does not move.
Step 4: Conclusion. Thus, in a suspended type moving coil galvanometer, the magnet is stationary.
04
PYQ 2020
medium
physicsID: mht-cet-
A capacitor is connected in series with another capacitor . The combination is connected across a d.c. source of 200 V. The ratio of potential across to that across is
1
8:1
2
16:1
3
2:1
4
4:1
Official Solution
Correct Option: (4)
Step 1: Understanding the behavior of capacitors in series. When capacitors are connected in series, the total capacitance is given by:
For and , we have:
Step 2: Voltage division across capacitors. The voltage across each capacitor in a series combination is inversely proportional to its capacitance. Therefore, the ratio of the potential across to that across is given by:
Substituting the values of and :
Step 3: Conclusion. Thus, the ratio of the potential across to that across is 4:1, which corresponds to option (D).
05
PYQ 2026
hard
physicsID: mht-cet-
The capacitance of an infinite circuit formed by the repetition of the same link consisting of two identical capacitors, each with capacitance , as shown in the figure is:
1
Zero
2
3
4
Infinite
Official Solution
Correct Option: (2)
Concept: For an infinite repeating network, the equivalent capacitance of the entire circuit remains the same even after removing the first repeating section. This self-similarity allows us to form an equation for the equivalent capacitance. Let the equivalent capacitance between points and be . Step 1: {Represent the infinite network using self-similarity.} After the first section, the remaining infinite network still has equivalent capacitance . The first section consists of:
One capacitor in series along the top branch
A vertical capacitor connected to the remaining network
Step 2: {Combine the vertical capacitor with the remaining network.} The vertical capacitor is in parallel with the equivalent capacitance of the remaining infinite network. Thus, Step 3: {Find equivalent capacitance of the series combination.} The series combination of and is Substitute : Step 4: {Solve the equation.} Dividing by : Step 5: {Solve the quadratic equation.} Thus, Hence, the correct option is (B).