Whose main job is giving strength and stiffness to a plant cell?
Cell wall gives the necessary strength and stiffness to the plant cell. You can read about the Plant Tissues –... View Article
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18 Aug 2021: The Hindu Analysis
UPSC Current Affairs Preparation: The Hindu Analysis Watch expert analysis of ‘The Hindu’ dated 18th Aug 2021. Important news and... View Article
In a magnesium rod of area 3m2, current I = 5A is flowing angle of 600 from the axis of the rod. The resistivity of the material is 44 × 10−2 ohm x m. Find an electric field inside the rod
a. 0.567 b. 0.367 c. 0.667 d. 0.767 Solution: Answer: (b) \(\begin{array}{l}\frac{I}{A_{effective}}=\frac{E}{\rho }\end{array} \) \(\begin{array}{l}E = \frac{\rho I}{A}cos 60^{0}=\frac{44\times 10^{-2}\times... View Article
A body of mass m emits a photon of frequency v, then loss in its internal energy?
a. \(\begin{array}{l}h\nu\end{array} \) b. \(\begin{array}{l}h\nu \left (1- \frac{h\nu }{2mc^{2}}\right )\end{array} \) c. \(\begin{array}{l}h\nu \left (1+ \frac{h\nu }{2mc^{2}}\right )\end{array} \) d.... View Article
Four planks are arranged in a lift going upwards with an acceleration of 0.2 m/s2 as shown in the figure. Find the normal reaction applied by the lift on 10 kg block:
a. 500 b. 700 c. 672 d. 800 Solution: Answer: (b) N – 70g = 70 x 0.2 N =... View Article
A particle of mass moving with a speed v collide elastically with the end of a uniform rod of mass M and length L perpendicularly as shown in the figure. If the particle comes to rest after collision, find the value of m/M.
a. 1/3 b. 1/2 c. 1/4 d. 1/5 Solution: Answer: (A) Applying conservation of angular momentum about the Centre of... View Article
A vehicle moving with velocity v and releasing the sound of frequency 400 Hz. Listening to the reflected sound from a wall of frequency 500 Hz. Find the velocity of vehicle
a. 36.67 m/s b. 30.12 m/s c. 22.37 m/s d. 20.25 m/s Solution: Answer: (a) Frequency received by wall \(\begin{array}{l}f’... View Article
The wavenumber of the spectral line in the emission spectrum of hydrogen will be equal to 8/9 times of the Rydberg’s constant. Then the electron jumps from
a. 5 → 2 b. 5 → 3 c. 3 → 1 d. 4 → 2 Solution: Answer: (c) \(\begin{array}{l}\bar{v}=Rz^{2}\left... View Article
A ball of charge to mass ratio of 8 μC/g is placed at a distance of 10 cm from the ball. An electric field of 100 N/m is switched on in the direction of the wall. Find the time period of its oscillations. Assume all collisions are elastic.
a. 1 sec b. 2 sec c. 3 sec d. 4 sec Solution: Answer: (a) \(\begin{array}{l}a =\frac{qE}{m}=\frac{8\times 10^{-6}}{10^{-3}}\times 100= 0.8m/s^{2}\end{array}... View Article
A travelling wave is found to have the displacement by y = 1/(1+x)2 at t = 0, after 3 sec the wave pulse is represented by equation y = 1/1+(1+x)2. The velocity of the wave is:
a. 1 m/s b. 1/3 m/s c. 2/3 m/s d. ¼ m/s Solution: Answer: (b) Displacement of wave, Δx =... View Article
A conducting rod of length l is moving perpendicular to the magnetic field. The rod moves from 0 to 2b while the field exists only from 0 to b. Find the graph for emf and power dissipated w.r.t x.
Solution: Answer: From the given figure it is clear that the field exists from 0 to b only, therefore, the... View Article
A spring with natural length l0 has a tension T1 when its length is l1 and the tension is T2 when its length is l2. The natural length of spring will be:
a. \(\begin{array}{l}\frac{T_{1}l_{2}-T_{2}l_{1}}{l_{1}-l_{2}}\end{array} \) b. \(\begin{array}{l}\frac{T_{2}l_{1}-T_{1}l_{2}}{T_{2}-T_{1}}\end{array} \) c. \(\begin{array}{l}\frac{T_{2}l_{2}-T_{1}l_{1}}{T_{1}-T_{2}}\end{array} \) d. \(\begin{array}{l}\frac{T_{2}l_{1}-T_{1}l_{2}}{T_{2}+T_{1}}\end{array} \) Solution: Answer: (b) Let the natural length be... View Article
Consider a body of 800 kg moving with a maximum speed v on a road banked at θ= 300 given cos 300 = 0.87. Find the normal reaction on the body. Coefficient of friction μs = 0.2. [Take radius, r = 10 m]
a. 10. 4 kN b. 12.6 kN c. 11.6 kN d. 8.3 kN Solution: Answer: (a) Since the circular motion... View Article
For an element decaying through simultaneous reaction, the half-life for the respective decaying path is 1400 S and 700 S. Find the time taken when the number of atoms becomes N0/3 in the element sample. (N0 is the initial number of atoms in sample)
a. (1400/5) In 3 b. (1400/3) In 3 c. (1400/3)ln 2 d. (700/3)ln 2 Solution: Answer: (b) N = N0et/τ... View Article
An object moves from the earth’s surface to the surface of the moon. The acceleration due to gravity on the earth’s surface is 10 m/s2…..
Question: An object moves from the earth’s surface to the surface of the moon. The acceleration due to gravity on... View Article
If [latex]\vec{A}.\vec{B}=\vec{A}\times \vec{B}[/latex] find [latex]\left | \vec{A}-\vec{B} \right |[/latex]
a. A – B b. \(\begin{array}{l}\sqrt{A^{2} + B^{2}-\sqrt{2AB}}\end{array} \) c. A + B d. \(\begin{array}{l}\sqrt{A^{2} + B^{2}-\sqrt{2}AB}\end{array} \) Solution: Answer:... View Article
In the circuit shown, find the current through the Zener diode.
a. 5 mA b. 1 mA c. 15 mA d. 25 mA Solution: Answer: (d) Since 2000 Ω is parallel... View Article
Deuteron and alpha particles having the same KE in a magnetic field. If the ratio of the radius of Deuteron and alpha particle is x√2. Then x =
a. 5 b. 8 c. 3 d. 1 Solution: Answer: (d) KE = B2q2r2/2m As B and KE are the... View Article
Bird is flying in north-east direction with or v = 4√2 m/s with respect to the wind and the wind blowing from north to south with speed 1 m/s. Find the magnitude of the displacement of the bird in 3 sec.
a. 5 m b. 15 m c. 10 m d. 20 m Solution: Answer: (b)
A charge Q is divided into q and (Q – q). If Q/q = x, such that the repulsion between them is maximum, find x.
a. 1 b. 2 c. 3 d. 4 Solution: Answer: (b) 2 As we know, F = (k(Q−q)q) /d2 For... View Article
