Assertion (A): When charges are shared between two bodies, there occurs no loss of charge, but there does occur a loss of energy.
Reason (R): In case of sharing of charges energy of conservation fails.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Total charge is always conserved during sharing. Electrical potential energy may decrease and convert to heat, implying 'loss' of electrical energy (A is true). However, total energy is always conserved; (R) is false because energy conservation never fails.
Assertion (A): Distance of closest approach for free target is more than that for fixed target.
Reason (R): Total energy is conserved for free target but not for fixed target.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
For a free target, kinetic energy is shared, reducing the effective kinetic energy, leading to a larger closest approach distance (A is true). For a free target, mechanical energy of interacting particles is conserved. For a fixed target, external forces do work, so mechanical energy of the interacting particles is not conserved (R is true). This difference explains (A).
Assertion (A): Distance of closest approach for free target is more than that for fixed target.
Reason (R): Total energy is conserved for free target but not for fixed target.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
For a free target, the target can recoil, sharing kinetic energy with the projectile, leading to less relative kinetic energy converted into potential energy, hence a larger distance of closest approach. Total energy is always conserved if only conservative forces are present for both free and fixed targets. Thus (A) is true and (R) is false.
Assertion (A): When two positive point charges move away from each other, their electrostatic potential energy decreases.
Reason (R): Change in potential energy between two points is equal to the work done by electrostatic forces.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A): Electrostatic potential energy between two positive charges is \(U = k \frac{q_1 q_2}{r}\). If they move away, \(r\) increases, thus \(U\) decreases. So (A) is true.
Reason (R): The change in potential energy is defined as the negative of the work done by conservative forces (like electrostatic force): \(Delta U = -W_{electrostatic}\). So (R) is false.nTherefore, (A) is true and (R) is false.