List of top Physics Questions

For the equation of force \(F = Aa^b d^c\), where \(F\) is the force, \(A\) is the area, \(v\) is the velocity and \(d\) is the density, the values of \(a, b\) and \(c\) are respectively:
A spherically symmetric gravitational system of particles has a mass density \[ \rho = \begin{cases} \rho_0 & \text{for } r \le R \\ 0 & \text{for } r > R \end{cases} \] where \(\rho_0\) is a constant. A test mass can undergo circular motion under the influence of the gravitational field of particles. Its speed \(v\) as a function of distance \(r\) \((0 < r < \infty)\) from the centre of the system is represented by:
A small block of mass \(m\) is kept on a rough inclined surface of inclination \(\theta\) fixed in an elevator. The elevator goes up with a uniform velocity \(v\) and the block does not slide on the wedge. The work done by the force of friction on the block in time \(t\) will be:
A train accelerating uniformly from rest attains a maximum speed of \(40 \text{ m s}^{-1}\) in 20 s. It travels at this speed for 20 s and is brought to rest with uniform retardation in further 40 s. What is the average velocity during the period?
A rifle man, who together with his rifle has a mass of 100 kg, stands on a smooth surface and fires 10 shots horizontally. Each bullet has a mass 10 g and a muzzle velocity of 800 m s\(^{-1}\). The velocity which the rifle man attains after firing 10 shots is:
A circular current carrying coil has a radius \( R \). The distance from the center of the coil on the axis, where the magnetic induction will be \( \frac{1}{8} \) to its value at the center of the coil is?
The incorrect statement regarding the lines of force of the magnetic field \( B \) is?
Two coils have a mutual inductance of 0.55 H. The current changes in the first coil according to the equation \( I = I_0 \sin \omega t \), where \( I_0 = 10 \, A \) and \( \omega = 100 \, \text{rad/s} \). The maximum value of emf in the second coil is?
An eye can detect \( 5 \times 10^4 \) photons per square meter per second of green light ( \( \lambda = 500 \, \text{nm} \)) while the ear can detect \( 10^{-12} \, \text{W/m}^2 \). The factor by which the eye is more sensitive as a power detector than ear is close to?
An L-C-R circuit contains \( R = 50 \, \Omega \), \( L = 1 \, \text{mH} \), and \( C = 0.1 \, \mu\text{F} \). The impedance of the circuit will be minimum for a frequency of?
During charging a capacitor, variations of potential \( V \) of the capacitor with time \( t \) is shown as?
When a resistor of 11 Ω is connected in series with an electric cell, the current following in it is 0.5 A. Instead, when a resistor of 5Ω is connected to the same electric cell in series, the current increases by 0.4 A. The internal resistance of the cell is?
A battery is charged at a potential of 15 V in 8 h when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 h. The mean terminal voltage during discharge is 14V. The watt-hour efficiency of the battery is?
Silver has a work function of 4.7 eV. When ultraviolet light of wavelength 100 nm is incident on it, a potential of 7.7 V is required to stop the photoelectrons from reaching the collector plate. How much potential will be required to stop photoelectrons when light of wavelength 200 nm is incident on it?
If the distance of 100 W lamp is increased from a photocell, the saturation current in the photocell varies with the distance \( d \) as?
Following process is known as?
If the electron in the hydrogen atom jumps from the third orbit to second orbit, the wavelength of the emitted radiation in terms of Rydberg constant is?
In hydrogen discharge tube, it is observed that through a given cross-section \( 3.31 \times 10^{15} \) electrons are moving from right to left and \( 3.12 \times 10^{8} \) protons are moving from left to right. The current in the discharge tube and its direction will be?
Which has more luminous efficiency?
The activity of a radioactive sample is measured as \( N_0 \) counts per minute at \( t = 0 \) and \( N \) counts per minute at \( t = 5 \) min. The time, in minutes, at which the activity reduces to half its value is?
A Zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in figure. The current through the diode is?
In a semiconductor, separation between conduction and valence band is of the order of?
The resistance of a germanium junction diode whose \( V-I \) is shown in figure is ( \( V_k = 0.3 \, V \))?
If 1000 droplets each of potential 1 V and radius \( r \) are mixed to form a big drop, then the potential of the drop as compared to small droplets will be?
A proton and an α-particle, accelerated through the same potential difference, enter a region of uniform magnetic field normally. If the radius of the proton orbit is 10 cm, then the radius of α-particles is?