List of top Physics Questions

A light emitting diode is (A) a n-p-n type semiconductor with a forward bias

In the context of p-n junction, select the correct statement from the following: (A) The barrier potential remains constant under forward bias

For signal transmission, modulation is necessary

A ball of mass 1 kg and radius 0.5 m, starting from rest rolls down on a $30^\circ$ inclined plane. The torque acting on the ball at the distance of 7 m from the starting point is close to (Take $g = 10 \text{ m/s}^2$) (A) 0.25 N-m

The radius of gyration about an axis through the center of a hollow sphere with external radius $a$ and internal radius $b$ is (A) \( \sqrt{\frac{2}{5}\frac{(a^{3}-b^{3})}{(a^{5}-b^{5})}} \)

If the radius of the earth suddenly decreases by half of its present value, the time duration of one day will be (A) 6 hours

The Brewster's angle for air to water interface is

In the amplitude modulation mode of transmission, the normal speech signal is with a maximum frequency of 5 kHz. If the carrier frequency is 200 kHz, the modulated signal will have the frequencies varying between

A TV transmitting antenna is 81 m tall. It has a half-power beam width of 10 degrees. If the receiving antenna is at the ground level, the service area covered by the transmitter is determined by

In a single slit diffraction (of width $\alpha$) by a monochromatic source of wavelength $\lambda$ the first minimum of the intensity distribution occurs at an angle

A monochromatic source of wavelength 600 nm was used in Young's double slit experiment to produce interference pattern. $I_1$ is the intensity of light at a point on the screen where the path difference is 150 nm. The intensity of light at a point where the path difference is 200 nm is given by

An object is placed at 9 cm in front of a concave mirror of radius of curvature 12 cm. The following statement is true:

An optician prescribes a lens of power +2.5 D. The focal length of the lens in water is (Indices: Lens = 1.5, Water = 1.33):

A parallel plate capacitor (of capacitance \( C \)) with circular plates of radius \( r_0 \) located at positions \( \pm \alpha \), is connected in series with a resistor \( R \) and is charged by a battery of voltage \( V \). Consider a circular loop \( L \) of radius \( \frac{r_0}{2} \) parallel to the capacitor plates is located at the center. Which of the following statements is correct?

The radiation produced by a 100 W bulb has the following property

The electric field of an electromagnetic wave in free space is given by \( \vec{E} = 5\sin\left(\tfrac{2\pi}{3}z - \omega t\right)\hat{y} \) V/m. Which of the following statements is correct?

The variation of speed (in m/s) of an object with time (in seconds) is given by the expression $V(t) = V_0 - 5t + 5t^2$

A boat is moving from the east bank to the west bank on a south flowing river. If the speed of the boat is 4 km/h and that of the river is 3 km/h. If the width of the river is 2 km, the distance travelled by the boat is

A bead is tied on one end of a stiff rope of length 1 m. With the other end of the rope as the center, the rope is rotated in such a way that the bead completes 10 revolutions per second. The centripetal acceleration of the bead is

An object, moving with velocity 5 m/s, undergoes an acceleration of 1 m/s$^2$ at time $t = 0$. If the object has a mass of 1 kg, the kinetic energy (KE) of the object at time $t = 5$ s is

The magnitude of deceleration required for a body, moving at a speed of 10 m/s to come to a complete halt at a distance of 100 m is:

The following plot gives the variation of acceleration (m/s$^2$) with time (s) for an object that started from rest at time $t = 0$ s. The velocity at time $t = 15$ s (V15) and at 25 s (V25), respectively are

The dimensions for pressure is:

Body A of mass 4m moving with speed u collides with another body B of mass 2m, at rest. The collision is head on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is:

Two parallel infinite line charges with linear charge densities \(+λ \frac Cm\) and \(-λ \frac Cm\) are placed at a distance of \(2R\) in free space. What is the electric field mid-way between the two line charges