List of top Physics Questions

The crystal structure can be studied by using

A body is projected horizontally with a velocity of $u$ $ m/s$ at an angle $ \beta $ with the horizontal. The kinetic energy at the highest point is $( \frac{ 3}{ 4} )^{th}$ of the initial kinetic energy. The value of $ \beta $ is

In a common emitter configuration, a transistor has $\beta = 50$ and input resistance $1\, k\Omega$. If the peak value of a.c. input is $0.01\, V$ then the peak value of collector current is

A body weighs 22.42 g and has a measured volume of 4.7 cc The possible errors in the measurement of mass and volume are 0.01 g and cc. Then the maximum error percentage in the density will be

$n$ identical droplets are charged to $V$ volt each. If they coalesce to form a single drop, then its potential will be

Figure shows a straight wire length $l$ carrying current $i$. The magnitude of magnetic field produced by the current at point $P$ is.

Experimental investigations show that the intensity of solar radiation is maximum for a wavelength $480 \,nm$ in the visible region. Estimate the surface temperature of sun. (Given Wien's constant $b = 2.88\times10^{-3} \,mK.)$

The reading of the ammeter in the following figure will be

If $x_1$ be the size of the magnified image and $x_2$ the size of the diminished image in Lens Displacement Method, then the size of the object is

There are a $25\, W -220\, V$ bulb and a $100\, W-220\, V$ line. Which electric bulb will glow more brightly?

Two light sources are said to be coherent if they are obtained from

Which of the following rays is emitted by a human body?

Zener diode is used for

For the current loops shown in the figure, Kirchhoff's loop rule for the loops $A H D C B A$ and AHDEFGA yields these equations respectively

For transistor action (1) Base, emitter and collector regions should have similar size and doping concentrations. (2) The base region must be very thin and lightly doped. (3) The emitter-base junction is forward biased and base-collector junction is reverse biased. (4) Both the emitter-base junction as well as the base-collector junction are forward biased. Which one of the following pairs of statements is correct?

$\upsilon_{1}$ is the frequency of the series limit of Lyman series, $\upsilon_{2}$ is the frequency of the first line of Lyman series and $\upsilon_{3}$ is the frequency of the series limit of the Balmer series. Then

A plano-convex lens is made of refractive index of $1.6 .$ The radius of curvature of the curved surface is $60\, cm$. The focal length of the lens is

Two thick wires and two thin wires, all of same material and same length, form a square in three different ways $P, Q$ and $R$ as shown in the figure. With correct connections shown, the magnetic field due to the current flow, at the centre of the loop will be zero in case of...........

A motorboat covers a given distance in $6$ hours moving downstream on a river. It covers the same distance in $10$ hours moving upstream. The time it takes to cover the same distance in still water is..........

There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then

A proton of mass $ 1.67 \times 10^{-27}\, kg$ enters a uniform magnetic field $1\, T$ of at point A shown in figure with a speed of $10^7\, ms^{-1}$ The magnetic field is directed normal to the plane of paper downwards. The proton emerges out of the magnetic field at point $C$, then the distance $AC$ and the value of angle $\theta $ will respectively be

A neutral water molecule $(H_2O)$ in its vapour state has an electric dipole moment of magnitude $6.4 \times 10^{-30} C-m$ . How far apart are the molecules centres of positive and negative charges?

A small coil is introduced between the poles of an electromagnet so that its axis coincides with the magnetic field direction. The number of turns is n and the cross-sectional area of the coil is $A$. When the coil turns through $180^{\circ}$ about its diameter, the charge flowing through the coil is $Q$. The total resistance of the circuit is $R$. What is the magnitude of the magnetic induction?

The ratio of the amounts of heat developed in the four arms of a balance Wheatstone bridge, when the arms have resistances $P = 100\, \Omega,\,Q = 10\, \Omega,\, R = 300\, \Omega$ and $S = 30\, \Omega$ respectively is

The attenuation in optical fibre is mainly due to