# 1. The magnetic field at the center of the current-carrying circular loop is B1. The magnetic field at a distance of √3 times radius of the given circular loop from the center on i... 1. The magnetic field at the center of the current-carrying circular loop is B1. The magnetic field at a distance of √3 times radius of the given circular loop from the center on its axis is B2. The value of B1/B2 will be: (a) 9:4 (b) 12:√5 (c) 8:1 (d) 5:3 2. Three point charges, each of charge q are placed on vertices of a triangle ABC, with AB=AC=5L, BC=6L. The electrostatic potential at mid-point of side BC will be (a) 1/48πϵ0L (b) 8q/36πϵ0L (c) 5q/24πϵ0L (d) q/16πϵ0L 3. To increase the current sensitivity of a moving coil galvanometer by 50%, its resistance is increased so that the new resistance becomes twice its initial resistance. By what factor does its voltage sensitivity change? (a) Decreases by 25% (b) Increases by 25% (c) Increases by 75% (d) Decreases by 75% 4. The velocity of nth orbit in Bohr model of hydrogen atom varies directly proportional to (a) 1/b (b) 1/n^2 (c) n^2 (d) 1/n 5. A nucleus disintegrates into two nuclear parts, which have their velocities in the ratio 2:1. The ratio of their nuclear sizes will be (a) 2:1 (b) 1:3/2 (c) 3/5:1 (d) 1:2:5 6. The quantum nature of light explains the observations on photoelectric effect as (a) there is a minimum frequency of incident radiation below which no electrons are emitted (b) the maximum kinetic energy of photoelectrons depends only on the frequency of incident radiation 7. When the metal surface is illuminated, electrons are ejected from the surface after some time (a) the photoelectric current is independent of the intensity of incident radiation. 8. A cylinder of radius r and length l is placed in an uniform electric field parallel to the axis of the cylinder. The total flux for the surface of the cylinder is given by (a) 2πr^2Eπr (b) (c) Eπr^2 (d) Eπr^2

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The question paper contains various physics problems related to electromagnetism, kinetic energy, atomic structure, and photoelectric effect, aimed at assessing knowledge in different areas of physics.

#### Answer

8:1

The final answer is 8:1

##### Answer for screen readers

The final answer is 8:1

#### More Information

The magnetic field at the center is derived using Biot-Savart law. For a point on the axis, the field decreases with distance, specifically at points farther than the radius, due to geometric spreading and cancellation effects.

#### Tips

Common mistake is not accounting for the distance correctly when applying the axial magnetic field formula.