List of top Physics Questions

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 ?

In an oscillator, for sustained oscillations, Barkhausen criterion is $A\beta$ equal to ($A =$ voltage gain without feedback, $\beta =$ feedback factor)

A particle moves along a circle of radius ?$r$? with constant tangential acceleration. If the velocity of the particle is ?$?$? at the end of second revolution, after the revolution has started then the tangential acceleration is

A modulated signal $C_m(t)$ has the form $C_m(t)=30$ sin $300 \pi t + 10$ (cos $200 \pi t -$ cos $400 \pi t$). The carrier frequency $f_{c}$, the modulating frequency (message frequency) $f_{\omega}$, and the modulation index $\mu$ are respectively given by :

A bottle has an opening of radius $a$ and length $b$. A cork of length $b$ and radius $(a+ \Delta a)$ where $(\Delta a < < a)$ is compressed to fit into the opening completely (See figure). If the bulk modulus of cork is $B$ and frictional coefficient between the bottle and cork is $\mu$ then the force needed to push the cork into the bottle is :

A student measures the time period of $100$ oscillations of a simple pendulum four times. The data set is $90\, s, 91\, s, 95\, s$ and $92\, s$. If the minimum division in the measuring clock is $1 \,s$, then the reported mean time should be :

A and B are two parallel sided transparent slabs of refractive indices n$_1 $and n$_2$ respectively. A ray is incident at an angle $\theta$ on the surface of separation of A and B, and after refraction from B into air grazes the surface of B. Then

Hysteresis loops for two magnetic materials $A$ and $B$ are given below : These materials are used to make magnets for electric generators, transformer core and electromagnet core. Then it is proper to use :

Identify the semiconductor devices whose characteristics are given below, in the order $(a), (b), (c), (d)$ :

A satellite is revolving in a circular orbit at a height ' $h$' from the earth's surface (radius of earth $R ; h < < R$). The minimum increase in its orbital velocity required, so that the satellite could escape from the earth?s gravitational field, is close to : (Neglect the effect of atmosphere.)

A pendulum clock loses $12\,s$ a day if the temperature is $40^{\circ}C$ and gains $4\,s$ a day if the temperature is $20^{\circ}C$. The temperature at which the clock will show correct time, and the co-efficient of linear expansion $(\alpha)$ of the metal of the pendulum shaft are respectively :

A ball is thrown from a point $A$ with a speed $u$ at an angle $\theta$ with the horizontal. If $g$ is the acceleration due to gravity, the total time taken for it to reach a point $B$ on the same horizontal plane is