List of top Physics Questions

Mass spectrometric analysis of potassium and argon atoms in a Moon rock sample shows that the ratio of the number of (stable) ${ }^{40} Ar$ atoms present to the number of (radioactive) ${ }^{40} K$ atoms is $10.3$. Assume that all the argon atoms were produced by the decay of potassium atoms, with a half-life of $1.25 \times 10^{9} yr$. How old is the rock?

Infrared radiations are detected by

In the diagram shown below all three rods are of equal length $L$ and equal mass $M$. The system is rotated such that rod $B$ is the axis. What is the moment of inertia of the system?

In an $L-R$ circuit, time constant is that time in which current grows from zero to the value where $ I_{0}$ is steady state current.

If the half-life of any sample of radioactive substance is $4$ days, then the fraction of sample will remain undecayed after $2$ days, will be?

If light is a longitudinal wave, it cannot explain

If the critical angle for total internal reflection from medium to vacuum is $ 30{}^\circ $ , the velocity of light in medium is

If average velocity becomes $4$ times then what will be the effect on rms velocity at that temperature?

In a potentiometer the null point is obtained at $7^\text{th}$ wire. If now we have to change the null point at $9^\text{th}$ wire, what should we do?

If $B_{H}=\frac{1}{\sqrt{3}} B_{v}$, find angle of dip. (where symbols have their usual meanings)

Graph of input characteristic of common emitter amplifier is

The earth moves in an elliptical orbit with the sun $S$ at one of foci as shown in the figure. Its rotational kinetic energy is maximum at the point

Reverberation time does not depend upon

The output is low when either of the input is high, then this represents which of the following gates?

If $C_p$ and $C_v$ denote the specific heats of nitrogen per unit mass at constant pressure and constant volume respectively, then

If a solid sphere of mass $1 \,kg$ and radius $0.1\, m$ rolls without slipping at a uniform velocity of $1\, m/s$ along a straight line on a horizontal floor, the kinetic energy is

For two resistance wires joined in parallel, the resultant resistance is $ \frac{6}{5}\Omega . $ When one of the resistance wires breaks the effective resistance becomes $ 2\,\Omega $ The resistance of the broken wire is

For the given uniform square lamina $ABCD$, whose centre is $O$,

For high frequency, capacitor offers

Diameter of human eye lens is $2 \,mm$. What will be the minimum distance between two points to resolve them, which are situated at a distance of $50 \,m$ from eye? The wavelength of light is $5000\,??.

Voltmeter is connected in parallel with the circuit Resistance of a voltmeter is very large.

Optical fibres are used for telecommunication Optical fibres are based on the phenomenon of total internal reflection.

NAND is a universal gate. It can be used to describe all other logic gates.

n: Light emitting diode $(LED)$ emits spontaneous radiation. : $LED$ are forward biased p-n junctions.

An astronaut experience weightlessness in a space satellite. When a body falls freely it does not experience gravity.