List of top Physics Questions

A reversible engine has an efficiency of \(\frac{1}{4}\). If the temperature of the sink is reduced by \(58^\circ\text{C}\), its efficiency becomes double. Calculate the temperature of the sink :
Which of the following equations is dimensionally incorrect ?
Where t = time, h = height, s = surface tension, \(\theta\) = angle, \(\rho\) = density, a, r = radius, g = acceleration due to gravity, v = volume, p = pressure, W = work done, \(\Gamma\) = torque, \(\epsilon\) = permittivity, E = electric field, J = current density, L = length.
For an ideal gas the instantaneous change in pressure 'p' with volume 'v' is given by the equation \(\frac{dp}{dv} = -ap\). If \(p = p_0\) at \(v = 0\) is the given boundary condition, then the maximum temperature one mole of gas can attain is : (Here R is the gas constant)
A coil having N turns is wound tightly in the form of a spiral with inner and outer radii 'a' and 'b' respectively. Find the magnetic field at centre, when a current I passes through coil :
Consider a galvanometer shunted with \( 5 \Omega \) resistance and \( 2% \) of current passes through it. What is the resistance of the given galvanometer ?
In an ac circuit, an inductor, a capacitor and a resistor are connected in series with \( X_L = R = X_C \). Impedance of this circuit is :
A small square loop of side 'a' and one turn is placed inside a larger square loop of side b and one turn (\( b \gg a \)). The two loops are coplanar with their centres coinciding. If a current I is passed in the square loop of side 'b', then the coefficient of mutual inductance between the two loops is :
A moving proton and electron have the same de-Broglie wavelength. If K and P denote the K.E. and momentum respectively. Then choose the correct option :

A zener diode of power rating 2 W is to be used as a voltage regulator. If the zener diode has a breakdown of 10 V and it has to regulate voltage fluctuated between 6 V and 14 V, the value of R\(_S\) for safe operation should be _________ \(\Omega\). 

 

Two simple harmonic motion, are represented by the equations
\(y_1 = 10 \sin\left(3\pi t + \frac{\pi}{3}\right)\)
\(y_2 = 5 (\sin(3\pi t) + \sqrt{3} \cos(3\pi t))\)
Ratio of amplitude of \(y_1\) to \(y_2=x: 1\). The value of x is _________.

Wires W\(_1\) and W\(_2\) are made of same material having the breaking stress of 1.25\(\times\)10\(^9\) N/m\(^2\). W\(_1\) and W\(_2\) have cross-sectional area of 8\(\times\)10\(^{-7}\) m\(^2\) and 4\(\times\)10\(^{-7}\) m\(^2\), respectively. Masses of 20 kg and 10 kg hang from them as shown in the figure. The maximum mass that can be placed in the pan without breaking the wires is _________ kg. (Use g = 10 m/s\(^2\)) 

 

A bullet of 10 g, moving with velocity v, collides head-on with the stationary bob of a pendulum and recoils with velocity 100 m/s. The length of the pendulum is 0.5 m and mass of the bob is 1 kg. The minimum value of v = _________ m/s so that the pendulum describes a circle. (Assume the string to be inextensible and g = 10 m/s\(^2\)) 

 

The ratio of the equivalent resistance of the network (shown in figure) between the points a and b when switch is open and switch is closed is x : 8. The value of x is _________. 

 

A constant magnetic field of 1 T is applied in the x \(>\) 0 region. A metallic circular ring of radius 1 m is moving with a constant velocity of 1 m/s along the x-axis. At t=0 s, the centre O of the ring is at x = -1 m. What will be the value of the induced emf in the ring at t=1s? (Assume the velocity of the ring does not change.) 

 

The colour coding on a carbon resistor is shown in the given figure. The resistance value of the given resistor is : 

 

Figure shows a rod AB, which is bent in a 120\(^{\circ}\) circular arc of radius R. A charge (\(-Q\)) is uniformly distributed over rod AB. What is the electric field \(\vec{E}\) at the centre of curvature O? 

 

Three capacitors C\(_1\) = 2 \(\mu\)F, C\(_2\) = 6 \(\mu\)F and C\(_3\) = 12 \(\mu\)F are connected as shown in figure. Find the ratio of the charges on capacitors C\(_1\), C\(_2\) and C\(_3\) respectively: 

 

The boxes of masses 2 kg and 8 kg are connected by a massless string passing over smooth pulleys. Calculate the time taken by box of mass 8 kg to strike the ground starting from rest. (use g = 10 m/s\(^2\)): 

 

Match List - I with List - II. 

Choose the most appropriate answer from the options given below : 
 

X different wavelengths may be observed in the spectrum from a hydrogen sample if the atoms are exited to states with principal quantum number n=6? The value of X is _________.
A plane electromagnetic wave with frequency of 30 MHz travels in free space. At particular point in space and time, electric field is 6 V/m. The magnetic field at this point will be \(x \times 10^{-8}\) T. The value of x is _________.
A tuning fork is vibrating at 250 Hz. The length of the shortest closed organ pipe that will resonate with the tuning fork will be _________ cm. (Take speed of sound in air as 340 ms\(^{-1}\))
A heat engine operates between a cold reservoir at temperature T\(_2\) = 400 K and a hot reservoir at temperature T\(_1\). It takes 300 J of heat from the hot reservoir and delivers 240 J of heat to the cold reservoir in a cycle. The minimum temperature of the hot reservoir has to be _________ K.
A monochromatic neon lamp with wavelength of 670.5 nm illuminates a photo-sensitive material which has a stopping voltage of 0.48 V. What will be the stopping voltage if the source light is changed with another source of wavelength of 474.6 nm ?
An ac circuit has an inductor and a resistor of resistance R in series, such that \(X_L = 3R\). Now, a capacitor is added in series such that \(X_C = 2R\). The ratio of new power factor with the old power factor of the circuit is \(\sqrt{5}:x\). The value of x is _________.