List of top Physics Questions

Radiation of wavelength $\lambda$, is incident on a photocell. The fastest emitted electron has speed $v$. If the wavelength is changed to $\frac{3 \lambda}{4}$, the speed of the fastest emitted electron will be :

Half-lives of two radioactive elements $A$ and $B$ are $20\, $ minutes and $40\,$ minutes, respectively. Initially, the samples have equal number of nuclei. After $80\,$ minutes, the ratio of decayed numbers of $A$ and $B$ nuclei will be :

To know the resistance $G$ of a galvanometer by half deflection method, a battery of emf $V_E$ and resistance $R$ is used to deflect the galvanometer by angle $\theta$. If a shunt of resistance $S$ is needed to get half deflection then $G, R$ and $S$ are related by the equation :

Two wires having same length and material are stretched by same force. Their diameters are in the ratio $1 : 3$. The ratio of strain energy per unit volume for these two wires (smaller to larger diameter) when stretched is

If the current in the toroidal solenoid increases uniformly from zero to $6.0\, A$ in $3.0?s.$ Self inductance of the toroidal solenoid is $40?H$. The magnitude of self induced emf is

When rigid body has neither linear acceleration nor angular acceleration then it is said to be in

A battery of constant voltage is available. How to adjust a system of three identical capacitors to get high electrostatic energy with the given battery

In vertical circular motion, the ratio of kinetic energy of a particle at highest point to that at lowest point is

A ring and a disc roll on the horizontal surface without slipping with same linear velocity. If both have same mass and total kinetic energy of the ring is $4\, J$ then total kinetic energy of the disc is

The current flowing through the 3$\Omega$ resistor in the circuit is,

Two identical wires $A$ and $B$, each of length $l$, carry the same current $I$. Wire $A$ is bent into a circle of radius $R$ and wire $B$ is bent to form a square of side $a$. If $B_A$ and $B_B$ are the values of magnetic field at the centres of the circle and square respectively, then the ratio $\frac{B_A}{B_B}$ is :

Two particles are performing simple harmonic motion in a straight line about the same equilibrium point. The amplitude and time period for both particles are same and equal to $A$ and $T$, respectively. At time $t = 0$ one particle has displacement $A$ while the other one has displacement $\frac{-A}{2}$ and they are moving towards each other. If they cross each other at time $t$, then $t$ is :

The box of a pin hole camera, of length $L$, has a hole of radius a. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength $\lambda $ the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size (say $b_{min}$) when :

A galvanometer having a coil resistance of $100 \, \Omega$ gives a full scale deflection, when a current of $1 \,mA$ is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of $10\, A$ is :

An arc lamp requires a direct current of $10\, A$ at $80 \,V$ to function. If it is connected to a $220 \,V \,(rms)$, $50 \,Hz\, AC$ supply, the series inductor needed for it to work is close to :

A particle performs simple harmonic motion with amplitude $A$. Its speed is trebled at the instant that it is at a distance $\frac{2A}{3}$ from equilibrium position. The new amplitude of the motion is :

A simple pendulum of length $l$ has maximum angular displacement $\theta$. The maximum kinetic energy of the bob of mass $m$ is ($g =$ acceleration due to gravity)

A series LCR circuit resonates at 10 kHZ. If the capacitor is 0.01 $\mu$F, the inductance used is approximately

An electron of mass ?m? is accelerated by a potential difference V and the corresponding de-Broglie wavelength is $\lambda$. The de Broglie wavelength of a proton of mass M if it is accelerated by the same potential difference is ,

The minimum and maximum capacitances, which may be obtained by the combination of three capacitors each of capacitance 6$\mu$ F are

Light is an electromagnetic wave whose

When the observer moves towards the stationary source with velocity, $V_1$, the apparent frequency of emitted note is $F_1$. When the observer moves away from the source with velocity $V_1$, the apparent frequency is $F_2$. If $V$ is the velocity of sound in air and $\frac{F_{1}}{F_{2}} = 2$ then $\frac{V}{V_{1}}=$ ?

A mass $m_1$ connected to a horizontal spring performs $S.H.M.$ with amplitude $A$. While mass $m_1$ is passing through mean position another mass $m_2$ is placed on it so that both the masses move together with amplitude $A_1$. The ratio of $\frac{A_{1}}{A}$ is $\left(m_{2} < m_{1}\right)$

A screw gauge with a pitch of $0.5\, mm$ and a circular scale with $50$ divisions is used to measure the thickness of a thin sheet of Aluminium. Before starting the measurement, it is found that when the two jaws of the screw gauge are brought in contact, the $45^{th}$ division coincides with the main scale line and that the zero of the main scale is barely visible. What is the thickness of the sheet if the main scale reading is $0.5\, mm$ and the $25^{th}$ division coincides with the main scale line ?