List of top Physics Questions

A boy walks to his school at a distance of 6 km with constant speed of ${2.5\, km \, h^{-1}}$ and walks back with a constant speed of ${4\, km \, h^{-1}}$. His average speed for round trip expressed in ${ km \, h^{-1}}$, is
A 280 day old radioactive substance shows an activity of 6000 dps, 140 days later its activity becomes 3000 dps. What was its initial activity?
X-rays, gamma rays and microwaves travelling in vacuum have
Two thin plano-convex lenses each of focal length $f$ are placed as shown in the figure. The ratio of their effective focal lengths in the three cases is
In the loop shown, the magnetic induction at the point $O$ is
A planet moving around sun sweeps area $A_1$ in $2$ days, $A_2$ in $3$ days and $A_3$ in $6$ days. Then the relation between $A_1, A_2 $ and $A_3$ is
When a mass is rotating in a plane about a fixed point, its angular momentum is directed along
If $v_e$ is escape velocity and $v _o$ is orbital velocity of a satellite for orbit close to the earth's suface, then these are related by
A car of mass m starts from rest and accelerates so that the instantaneous power delivered to the car has a constant magnitude $P_0$. The instantaneous velocity of this car is proportional to

Three blocks of masses m₁, m₂, and m₃ are connected by massless strings on a frictionless table and pulled by a force T₃ = 40 N. If m₁ = 10 kg, m₂ = 6 kg, and m₃ = 4 kg, the tension T₂ will be:

A massless platform is kept on a light elastic spring. When a sand particle of mass 0.1 kg is dropped from a height of 0.24 m, the spring compresses by 0.01 m. From what height should the particle be dropped to cause a compression of 0.04 m?

A mass m is suspended from a spring of force constant k and another identical spring is fixed to the floor as shown. The time period of small oscillations is:

In a uniformly charged sphere of total charge Q and radius R, the electric field E is plotted as a function of distance r from the centre. Which graph correctly represents this variation? 

A steady current is set up in a cubic network composed of wires of equal resistance and length as shown. What is the magnetic field at the centre P due to the cubic network?

Calculate the effective resistance between points A and B in the given electrical network.


Which one of the following curves represents the variation of impedance Z with frequency f in a series LCR circuit? 



 

Two vectors A and B are such that | A+ B|=| A- B|. The angle between them is:
In a semiconductor diode, the barrier potential offers opposition to:
The output of an OR gate is connected to both inputs of a NAND gate. The combination serves as:
Which one is correct about fission?
An electron in a hydrogen-like atom is in an excited state. It has total energy of -3.4 eV. The kinetic energy and de-Broglie wavelength respectively are:
If the distance between first maxima and fifth minima of a double slit pattern is 7 mm and the slits are separated by 0.15 mm with the screen 50 cm away, the wavelength of light used is:
The energies of energy levels A, B and C are EA < EB < EC. If the radiations of wavelengths ₁, ₂, ₃ are emitted due to transitions C to B, B to A and C to A respectively, then which relation is correct?
A metal rod of length 1 m is rotated about one of its ends in a plane perpendicular to a magnetic field of induction 2.5 × 10⁻³Wb/m². If it makes 1800 revolutions per minute, calculate the emf induced between its ends.
A thin convergent glass lens (= 1.5) has a power of +5.0 D. When this lens is immersed in a liquid of refractive index μ, it acts as a divergent lens of focal length 100 cm. The value of μ must be: