For the given graph between decay rate and time find half-life (where R = decay rate)
a. 10 / 3 ln2 b. 20 / 3 ln2 c. 3 / 20 ln2 d. 3 / 10 ln2... View Article
Latest Posts
A person walks up a stationary escalator in the time t1. If he remains stationary on the escalator, then it can take him up in time t2. Determine the time it would take to walk upon the moving escalator?
a. \(\begin{array}{l}\frac{t_{1}t_{2}}{t_{1}+t_{2}}\end{array} \) b. \(\begin{array}{l}\frac{t_{1}t_{2}}{t_{1}-t_{2}}\end{array} \) c. \(\begin{array}{l}\frac{2t_{1}t_{2}}{t_{1}+t_{2}}\end{array} \) d. \(\begin{array}{l}\frac{2t_{1}t_{2}}{t_{1}-t_{2}}\end{array} \) Solution: Answer: (a) Suppose length of escalator =... View Article
A satellite is revolving around a planet in an orbit of radius R. Suddenly radius of orbit becomes 1.02 R, then what will be the percentage change in its time period of revolution?
a. 2% b. 3% c. 5% d. 7% Solution: Answer: (b) \(\begin{array}{l}T \alpha R^{\frac{3}{2}}\end{array} \), \(\begin{array}{l}T = kR^{\frac{3}{2}}\end{array} \), \(\begin{array}{l}\frac{\Delta... View Article
A RLC circuit is in its resonance condition. Its circuit components have value R = 5Ω, L = 2H, C = 0.5mF, V= 250V. Then find the power in the circuit.
a. 6 kW b. 10 kW c. 12 kW d. 12.5 kW Solution: Answer: (d) As the circuit is in... View Article
If the kinetic energy of a particle becomes four times, then % change in momentum will be
a. 200 b. 100 c. 150 d. 50 Solution: Answer: (b) K.E. ⇒ K = P2 / 2m P ∝... View Article
Three sound waves of equal amplitudes have frequencies (v-1), v, (v+1). They superpose to give beats. The number of beats produced per second will be
(a) 1 (b) 2 (c) 3 (d) 4 Solution: (b) 2 Beat produced between(v-1) and v is 1. Beat produced... View Article
When two sinusoidal waves moving at right angle to each other superimpose, they produce
(a) beats (b) Lissajous figure (c) interference (d) stationary waves Solution: (b) Lissajous figure If two SHMs act in perpendicular... View Article
Two coherent monochromatic beams of intensities I and 4I respectively are superposed. The maximum and minimum intensities in the resulting pattern are:
(a) 5I and 2I (b) 9I and I (c) 4I and 3I (d) 5I and I Solution: (b) 9I and... View Article
A sine wave is travelling in a medium. The minimum distance between the two particles, always having same speed, is
(a) λ/4 (b) λ/3 (c) λ/2 (d) λ Solution: (c) λ/2 In a sine wave, the particles on the string... View Article
The ratio of speed of sound in Hydrogen to that in Oxygen at the same temperature is
(a) 16:1 (b) 1: 4 (c) 2:3 (d) 4:1 Solution: (d) 4:1 Speed of sound in a medium = v... View Article
A particle on the trough of a wave at any instant will come to the mean position after a time. (T= time period)
(a) T (b) 2T (c) T/2 (d) T/4 Solution: (d) T/4 Here T be the total time taken by a... View Article
When sound travels from air to water, the quantity that remains unchanged is:
(a) speed (b) wavelength (c) intensity (d) frequency Solution: (d) frequency When sound travels from one medium to another the... View Article
At a certain instant a stationary transverse wave is found to have maximum kinetic energy. The appearance of string at that instant is.
(a) Sinusoidal shape with amplitude A/3. (b) Straight line (c) Sinusoidal shape with amplitude A/2. (d) Sinusoidal shape with amplitude... View Article
A boat at anchor is rocked by waves whose crests are 100m apart and velocity is 25m/s. The boat bounces up once in every
(a) 2500 s (b) 75 s (c) 4s (d) 0.25 s Solution: (c) 4s The boat bounces up, which means,... View Article
The angle between particle velocity and wave velocity in transverse waves is
(a) zero (b) π/4 (c) π/2 (d) π Solution: (c) π/2 In transverse waves the particles of the medium vibrate... View Article
If the speed of a wave doubles as it passes from shallow water into deeper water, its wavelength will be
(a) unchanged (b) doubled (c) quadrupled (d) halved Solution: (b) doubled Speed = frequency × wavelength When a wave passes... View Article
A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distances of 9m and 25m respectively from the source. The ratio of the amplitudes of the waves at P and Q is
(a) 9:4 (b) 1: 22 (c) 25:9 (d) 625:81 Solution: (c) 25:9 I = P/4πr2 and I α A2 And... View Article
The distance between two points differing in phase by 60o on a wave having a wave velocity 360 m/s and frequency 500 Hz is
(a) 0.72 m (b) 0.18 m (c) 0.12m (d) 0.32m Solution: (c) 0.12m Wavelength of wave = velocity/frequency = 360/500... View Article
Sound waves transfer
(a) energy (b) Momentum (c) Both energy and momentum (d) only energy not momentum Solution: (c) Both energy and momentum... View Article
A wave of frequency 500 Hz has a velocity of 360 ms-1. Calculate the distance between two points that are 60o out of phase
(a) 12 cm (b) 18 cm (c) 17 cm (d) 25 cm Solution: (a) 12 cm wavelength = velocity/frequency =... View Article
