List of top Physics Questions

Two polaroids are kept crossed to each other. If one of them is rotated an angle 60°, the percentage of incident light now transmitted through the system is
When sunlight is scattered by atmospheric atoms and molecules the amount of scattering of light of wavelength 880 nm is \( A \). Then, the amount of scattering of light of wavelength 330 nm is approximately
An electromagnetic wave propagating along north lies its electric field vertically upward. The magnetic field vector points towards
Pick out the wrong statement.
A ray of light is incident on a plane mirror at an angle of 30°. At what angle with the horizontal must a plane mirror be placed so that the reflected ray becomes vertically upwards?
An induced emf has
A coil of area 5 cm² having 20 turns is placed in a uniform magnetic field of \( 10^3 \, \text{gauss} \). The normal to the plane of coil makes an angle 30° with the magnetic field. The flux through the coil is
A compound microscope having magnifying power 35 with its eye-piece of focal length 10 cm. Assume that the final image is at least distance of distinct vision then the magnification produced by the objective is
The refractive index for a prism is given as \( \mu = \cot \frac{A}{2} \). Then, angle of minimum deviation in terms of angle of prism is
The value of inductance \( L \) for which the current is maximum in series \( LCR \) circuit with \( C = 10 \, \mu F \) and \( R = 1000 \, \Omega \) is
The current graph for resonance in an \( LC \) circuit is
A horizontal rod of mass 0.01 kg and length 10 cm is placed on a frictionless plane inclined at an angle 60° with the horizontal and with the length of the rod parallel to the edge of the inclined plane. A uniform magnetic field is applied ‘Vertically downwards’. The current through the rod is 1.7 A, then the value of magnetic field induction \( B \) for which the rod remains stationary in the inclined plane is
A current of 2 A is flowing in the sides of an equilateral triangle of side 9 cm. The magnetic field at the centroid of the triangle is
The direction of magnetic field \( dB \) due to current element \( dl \) at a distance \( r \) is the direction of
The earth is considered as a short magnet with its centre coinciding with the geometric centre of earth. The angle of dip \( \delta \) related to the magnetic latitude \( \lambda \) is
A magnetic needle lying parallel to the magnetic field requires \( W \) units of work to turn it through an angle 45°. The torque required to maintain the needle in this position will be
A galvanometer with a scale divided into 100 equal divisions has a current sensitivity of 10 divisions per milliampere and a voltage sensitivity of 2 divisions per millivolt. The galvanometer resistance will be
Which of the following statement related to hysteresis loop is incorrect?
The magnetic field at the centroid of the triangle is
The masses of three copper wires are in the ratio 3 : 2 : 5 and their lengths are in the ratio 3 : 2 : 5. Then, the ratio of their electrical resistances is
A 30V-90W lamp is operated on a 120V DC line. A resistor is connected in series with the lamp in order to glow it properly. The value of resistance
In a potentiometer experiment, the balancing length of a cell is 560 cm. When an external resistance of 10 \(\Omega\) is connected in parallel to the cell, the balancing length changes by 60 cm. The internal resistance of a cell is
Two sources of equal emf are connected to a resistance \( R \). The internal resistance of the sources are \( r_1 \) and \( r_2 \), \( (r_1>r_2) \). If the potential difference across the source having internal resistance \( r_2 \) is zero, then
An electron of mass \( 9.0 \times 10^{-31} \) kg under the action of a magnetic field moves in a circle of radius 2 cm at a speed of \( 3 \times 10^6 \) m/s. A proton of mass \( 1.8 \times 10^{-27} \) kg moves in a circle of same radius in the same magnetic field, then its speed will become
A condenser of capacitance \( C \) is fully charged by a 200V supply. It is then discharged through a small coil of resistance \( r \) embedded in thermally insulated block of specific heat 250 J/K-g and mass 100 g. If the temperature of the block rises by 0.4 K, then the value of \( C \) is