List of top Physics Questions

If the temperature of the body is increased by $ 10\%, $ the percentage increase in the emitted indication will be

A bar magnet of length '$l$' and magnetic dipole moment 'M' is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be

In which of the following statements, the obtained impure semiconductor is of $p$-type ?

A fluid is in streamline flow across a horizontal pipe of variable area of cross section. For this which of the following statements is correct?

An electric dipole of dipole moment $p$ is aligned parallel to a uniform electric field $E$. The energy required to rotate the dipole by $ 90^\circ $ is :

For photoelectric emission from certain metal the cutoff frequency is v. If radiation of frequency 2v impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass) :

The wavelength $\lambda_e$ of an electron and $\lambda_P$ of a photon of same energy E are related by:

In a common emitter $(CE)$ amplifier having a voltage gain $G$, the transistor used has transconductance $0.03 \,mho$ and current gain $25$. If the above transistor is replaced with another one with transconductance $0.02$ $mho$ and current gain $20$, the voltage gain will be :

In an unbiased $p-n$ junction, holes diffuse from the $p$-region to $n$-region because of

If value of surface tension of a liquid is 70 dyne/cm, then its value in N/m will be

Two point dipoles of dipole moment $\overrightarrow{p_{1}}$ and $\overrightarrow{p_{2}}$ are at a distance $x$ from each other and $\overrightarrow{p_{1}} \left|\right| \overrightarrow{p_{2}}.$ The force between the dipoles is :

A plane electromagnetic wave in a non-magnetic dielectric medium is given by $\vec{E}=\vec{E}_{0}\left(4\times10^{-7}\,x-50t\right)$ with distance being in meter and time in seconds. The dielectric constant of the medium is:

The shown p- V diagram represents the thermodynamic cycle of an engine, operating with an ideal monoatomic gas. The amount of heat, extracted from the source in a single cycle is

Two coherent point sources $S_1$ and $S_2$ are separated by a small distance $d$ as shown. The fringes obtained on the screen will be

A beam of unpolarized light of intensity $I_0$ is passed through a polaroid $A$ and then through another polaroid $B$ which is oriented so that its principal plane makes an angle of 45$^{\circ}$ relative to that of $A$. The intensity of the emergent light is

An ideal gas enclosed in a vertical cylindrical container supports a freely moving piston of mass $M$. The piston and the cylinder have equal cross-sectional area $A$. When the piston is in equilibrium, the volume of the gas is $V_0$ and its pressure is $P_0$. The piston is slightly displaced from the equilibrium position and released. Assuming that the system is completely isolated from its surrounding, the piston executes a simple harmonic motion with frequency

Two charges, each equal to $q$, are kept at $x = - a$ and $x = a$ on the $x-axis$. A particle of mass m and charge $q_0=\frac{q}{2}$ is placed at the origin. If charge $q_0$ is given a small displacement $y ( y << a)$ along the y-axis, the net force acting on the particle is proportional to

Diameter of a plano-convex lens is $6 \,cm$ and thickness at the centre is 3 mm. If speed of light in material of lens is $2 \times 10^8$ m/s, the focal length of the lens is

A $12.5\, eV$ electron beam is used to bombard gaseous hydrogen at room temperature. It will emit :

The gravitational field, due to the 'left over part' of a uniform sphere (from which a part as shown, has been 'removed out'), at a very far off point, \(P\), located as shown, would be (nearly):

A block is placed on a rough horizontal plane. A time dependent horizontal force $F = kt$ acts on the block, where $k$ is a positive constant. The acceleration - time graph of the block is:

A diatomic gas is heated at constant pressure. What fraction of the heat energy is used to increase the internal energy?

A red flower kept in green light will appear

The maximum current that can flow in the fuse wire before it blows out, varies with the radius \(r\) as