General Physics

Step 1: Understanding the Wheatstone bridge.
A Wheatstone bridge is a circuit used to measure an unknown resistance by balancing two legs of a bridge circuit. The bridge consists of four resistances, and the unknown resistance is calculated when the bridge is balanced (i.e., when the current through the galvanometer is zero).
Step 2: Conclusion.
Thus, a Wheatstone bridge is primarily used to measure resistance, corresponding to option (C).

Step 1: Understanding Coulomb's Law.
According to Coulomb's law, the force between two point charges is given by the equation: where is Coulomb's constant, and are the magnitudes of the charges, and is the distance between them.
Step 2: Effect of halving the distance.
If the distance is halved, the force becomes: Step 3: Conclusion.
Thus, when the distance between the charges is halved, the force between the charges becomes four times larger, corresponding to option (C).

Step 1: Understanding the relationship between RMS and peak voltage.
The relationship between the RMS value and peak value of an AC voltage is given by the formula: where is the RMS (Root Mean Square) value.
Step 2: Substituting the given value.
For , we get: Step 3: Conclusion.
Thus, the peak value of 220 V AC is , corresponding to option (B).

Step 1: Formula for resistance in series.
When resistances are connected in series, the total resistance is the sum of the individual resistances: where and are the resistances of the individual resistors.
Step 2: Conclusion.
Thus, the total resistance in a series circuit is the sum of the individual resistances.

Step 1: Using Coulomb’s law.
Coulomb’s law gives the force between two point charges and separated by a distance : where is Coulomb's constant, and are the charges, and is the distance between them.
Step 2: Substituting values.
The charge on a proton and electron is . The distance . Substituting these values into Coulomb's law: Step 3: Conclusion.
Thus, the Coulomb force between the proton and electron is .

Step 1: Understanding transformer efficiency.
The efficiency of a transformer is determined by how well it converts input power to output power. Factors that reduce transformer efficiency include:
- **Core losses (hysteresis and eddy current losses):** These are the losses that occur due to the alternating magnetic field in the transformer core, leading to heat generation.
- **Copper losses:** These occur due to the resistance of the windings in the transformer. As current flows through the windings, energy is lost as heat.
- **Leakage flux:** Not all magnetic flux produced by the primary coil links with the secondary coil, leading to energy loss.
- **Load losses:** These losses increase as the load on the transformer increases.
- **Iron losses:** These occur due to the resistance of the transformer core to the changing magnetic field.
Step 2: Conclusion.
Thus, core losses, copper losses, leakage flux, and load losses are some of the factors that reduce the efficiency of a transformer.