Browse and search thousands of solved questions for your preparation.
Free questions with full explanations — locked behind signup to protect quality.
A parallel beam of fast-moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct?
Under the influence of a uniform magnetic field, a charged particle moves with constant speed v in a circle of radius R. The time period of rotation of the particle -
A galvanometer having a coil resistance of 60 $\Omega$ shows full scale deflection when a current of 1.0 A passes through it. It can be converted into an ammeter to read currents upto 5.0 A by
The unit of reduction factor of the tangent galvanometer is:
A galvanometer of resistance 50 Ω is connected to a battery of 3 V along with a resistance of 2950 Ω in series. A full-scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to 20 divisions, the resistance in series should be:
When a 12 \Omega resistor is connected in parallel with a moving coil galvanometer, its deflection reduces from 50 divisions to 10 divisions. What will be the resistance of the galvanometer?
Eight dipoles of charges of magnitude $e$ are placed inside a cube. The total electric flux coming out of the cube will be:
Each of the two strings of length $51.6 \text{ cm}$ and $49.1 \text{ cm}$ are tensioned separately by $20 \text{ N}$ force. Mass per unit length of both the strings is same and equal to $1 \text{ g m}^{-1}$. When both the strings vibrate simultaneously the number of beats is:
The efficiency of a Carnot engine depends upon:
A galvanometer of resistance G is shunted by a resistance S ohm. To keep the main current in the circuit unchanged, the resistance to be put in series with the galvanometer is
A voltmeter has a resistance of $G$ ohms and range $V$ volts. The value of resistance used in series to convert it into a voltmeter of range $nV$ volts is:
The net resistance of a voltmeter should be large to ensure that:
If a charged particle (charge q) is moving in a circle of radius R at a uniform speed v, then the value of its associated magnetic moment μ will be:
A wheel with 20 metallic spokes, each 1 m long, is rotated with a speed of 120 rpm in a plane perpendicular to a magnetic field of 0.4 G. The induced emf between the axle and rim of the wheel will be: (1 G = 10⁻⁴ T)
A metallic rod of mass per unit length of 0.5 kg m⁻¹ is lying horizontally on a smooth inclined plane which makes an angle of 30° with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction of 0.25 T is acting on it in the vertical direction. What is the current flowing through the rod to keep it stationary?
Two spheres A and B of masses $m_1$ and $m_2$ respectively collide. A is at rest initially and B is moving with velocity $v$ along x-axis. After collision B has a velocity $\frac{v}{2}$ in a direction perpendicular to the original direction. The mass A moves after collision in the direction:
A 250 turn rectangular coil of length $2.1 \text{ cm}$ and width $1.25 \text{ cm}$ carries a current of $85 \, \mu\text{A}$ and subjected to the magnetic field of strength $0.85 \text{ T}$. Work done for rotating the coil by $180^{\circ}$ against the torque is:
Ionized hydrogen atoms and $\alpha$-particles with the same momenta enter perpendicular to a constant magnetic field, $B$. The ratio of their path radii $r_H : r_\alpha$ will be:
An LED is constructed from a p-n junction diode using GaAsP. The energy gap is $1.9 \text{ eV}$. The wavelength of the light emitted will be equal to:
For the circuit shown in the figure, the time constant is: