List of top Physics Questions

A uniform wire has length L and radius r. It is acted on by a force F as shown. The elongation is l. If F and r are both halved, the new elongation will be :

The truth table for the combination of logical gates

Find the ratio of the charge on $4$ $µF$ to that on $2$ $µF$ in steady state.

A ball of mass $120$ $g$ moving with initial velocity $25 \;m/s$ is stopped by an external force $F$ in $0.15$ $sec$. Find value of $F$ in newton :

Find the number of significant digits in the value 10.05

Two trains run on North-South parallel tracks. Train A moves with velocity 20 m/s towards North and train B moves with velocity 30 m/s towards South. Then find the velocity of train B with respect to train A

Two particles each of mass $2$ kg are places as shown in $x→ y$ plane. If the distance of centre of mass from origin is $\frac{4\sqrt 2}{x}$ find $x$ :

The length of a seconds pendulum if it is placed at height $2R$ from the surface of the earth (R: radius of earth) is $\frac{10}{xπ^2}$ $m$. Find $x$

If the mass defect in a nuclear reaction is $0.4$ $gm$ then find the $Q$ value of the reaction.

Potential energy function corresponding to conservative force is given as $U(x, y, z) = \frac{3x^2}{2} + 5y + 6z$ then the force at $x = 6$ is $pN$. The value of $p$ upto $2$ its nearest integral value is

A thin liquid film formed between a U-shaped wire and a light slider supports a weight of $1.5 \times 10^{-2}$ $N$. The length of the slider is $30\ cm$ and its weight negligible. The surface tension of the liquid film is -

A series LCR circuit is connected to a 45 sin (ωt) volt source. The resonant angular frequency of the circuit is 10⁵ rad/sec and the current amplitude at resonance is I₀. When the angular frequency of the source is ω = 8 x 10⁴ rad/sec, the current amplitude in the circuit is 0.05 I₀. If m = 50 mH, match each entry in the list - I with an approximate value from list - II and choose the option.

	List - I		List - II
(P)	I₀ in mA	(1)	44.4
(Q)	The quality factor of the circuit	(2)	18
(R)	The bandwidth of the circuit in rad/sec	(3)	400
(S)	The peak power dissipated at resonance in watt	(4)	2250
		(5)	500

A square loop of side 2 cm enters a magnetic field with a constant speed of 2 cm s^-1 as shown. The front edge enters the field at t = 0s. Which of the following graph correctly depicts the induced emf in the loop?
( Take clockwise direction positive )

A stretched wire of a material whose Young's modulus Y = 2 × 10¹¹ Nm^-2 has Poisson's ratio of 0.25. Its lateral strain ε_l = 10^-3. The elastic energy density of the wire is

The Wheatstone bridge shown in the diagram is balanced. If P3 is the power dissipated by R3 and P1 is the power dissipated by R1, then the ratio P3/P1 is:

A horizontal bridge is built across a river. A student standing on the bridge throws a small ball vertically upwards with a velocity $4\ ms^{-1}$. The ball strikes the water surface after $4s$. The height of bridge above water surface is
(Take: $g=10\ ms^{-2}$)

For a given vector $\vec{F}=-y\hat{i}+z\hat{j}+x^2\hat{k}$ , the surface integral $\int_S(\vec{▽}\times \vec{F}).\hat{r}dS$ over the surface S of a hemisphere of radius R with the centre of the base at the origin is