Class 12 Physics 2023 Board Exam

Figure shows variation of Coulomb force (F) acting between two point charges with $1/r^2$, r being the separation between the two charges ($q_1,q_2$) and ($q_2,q_3$). If $q_2$ is positive and least in magnitude, then the magnitudes of $q_1,q_2$ and $q_3$ are such that
(A) $q_2<q_3<q_1$
(B) $q_3<q_1<q_2$
(C) $q_1<q_2<q_3$
(D) $q_2<q_1<q_3$

Two identical point charges are placed at the two vertices A and B of an equilateral triangle ABC. If M is the mid-point of AB, the net electric field at C will point along
(A) CA
(B) CB
(C) MC
(D) CM

In the figure curved lines represent equipotential surfaces. A charge Q is moved along different paths A, B, C and D. The work done on the charge will be maximum along the path
(A) A
(B) B
(C) C
(D) D

Two wires P and Q are made of the same material. The wire Q has twice the diameter and half the length as that of wire P. If the resistance of wire P is R, the resistance of the wire Q will be
(A) R
(B) R/2
(C) R/8
(D) 2R

A student has three resistors, each of resistance R. To obtain a resistance $\frac{2}{3}R$, she should connect
(A) all the three resistors in series.
(B) all the three resistors in parallel.
(C) two resistors in series and then this combination in parallel with the third resistor.
(D) two resistors in parallel and then this combination in series with the third resistor.

A 1 cm segment of a wire lying along x-axis carries current of 0.5 A along +x direction. A magnetic field $\vec{B}=(0.4mT)\hat{j}+(0.6mT)\hat{k}$ is switched on, in the region. The force acting on the segment is
(A) $(2\hat{j}+3\hat{k})$ mN
(B) $(-3\hat{j}+2\hat{k})$ $\mu$N
(C) $(6\hat{j}+4\hat{k})$ mN
(D) $(-4\hat{j}+6\hat{k})$ $\mu$N

The alternating current I in an inductor is observed to vary with time t as shown in the graph for a cycle.
Which one of the following graphs is the correct representation of wave form of voltage V with time t ?
(A) [Graph]
(B) [Graph]
(C) [Graph]
(D) [Graph]

The magnetic field due to a small magnetic dipole of dipole moment 'M' at a distance 'r' from the centre along the axis of the dipole is given by
(A) $\frac{{\mu }_0}{4\pi }\times \frac{2M}{r^3}$
(B) $\frac{{\mu }_0}{4\pi }\times \frac{M}{r^3}$
(C) $\frac{{\mu }_0}{4\pi }\times \frac{M}{2r^3}$
(D) $\frac{{\mu }_0}{4\pi }\times \frac{2M}{r^2}$

A diamagnetic substance is brought, one by one, near the north pole and the south pole of a bar magnet. It is
(A) repelled by north pole and attracted by south pole.
(B) attracted by north pole and repelled by south pole.
(C) attracted by north pole as well as by south pole.
(D) repelled by north pole as well as by south pole.

A circular coil of diameter 15 mm having 300 turns is placed in a magnetic field of 30 mT such that the plane of the coil is perpendicular to the direction of magnetic field. The magnetic field is reduced uniformly to zero in 20 ms and again increased uniformly to 30 mT in 40 ms. If the emfs induced in the two time intervals are $e_1$ and $e_2$ respectively, then the value of $e_1/e_2$ is
(A) $\frac{1}{2}$
(B) 1
(C) 2
(D) 4