List of top Physics Questions

In thermodynamic isobaric process
A soap bubble of radius R is blown. After heating the solution, a second bubble of radius 2R is blown. The work required to blow the second bubble in comparison to that required for the first bubble is
The excess pressure inside the first soap bubble of radius \(R_1\) is three times that inside the second soap bubble of radius \(R_2\). The ratio of volumes of the first bubble to second bubble is
An ordinary body cools from \(4θ\) to \(3θ\) in 't' minutes. The temperature of the body after next 't' minutes is (Assume Newton's law of cooling and room temperature as \(θ\))
A black disc has a radius 'R' and wavelength corresponding to the maximum intensity is '\(λ\)'. The emissive power (E) for the different radii and maximum wavelengths is directly proportional to
Water rises to a height \(3\) cm in a capillary tube. If cross-sectional area of capillary tube is reduced to \(1/3^{rd}\) of its initial area then water will rise to a height of
What should be the angular velocity of earth due to rotation about its own axis so that the weight at equator becomes \((\frac{3}{5})^{th}\) of initial value? (\(g =\) acceleration due to gravity, R = radius of earth)
A vector \(\overset{⃗}{A}\) when added to the sum of the vectors \((\hat{i}-2\hat{j}+2\hat{k})\) and \((-2\hat{i}+\hat{j}-\hat{k})\) gives a unit vector along Y axis. The magnitude of vector \(\overset{⃗}{A}\) is
The power (P) is supplied to rotating body having moment of inertia 'I' and angular acceleration '\(α\)'. Its instantaneous angular velocity is
A particle performing U.C.M. of radius \(\frac{π}{2}\) m makes 'x' revolutions in time t. Its tangential velocity is
If the earth suddenly contracts to \((\frac{1}{3})^{rd}\) of its present size without change in its mass, the ratio kinetic energy of the earth after and before contraction will be (Earth is assumed to be a rotating sphere about itself)
Two masses \(m_1\) and \(m_2\) moving with velocities \(V_1\) and \(V_2\) in opposite directions collide elastically and after collision \(m_1\) and \(m_2\) move with velocities \(V_2\) and \(V_1\) respectively. The ratio \(\frac{m_2}{m_1}\) is
The length of rod is measured by meter scale having least count \(0.1\) cm and diameter is measured by vernier callipers having least count \(0.01\) cm. Length of rod is \(5.0\) cm and radius \(2.0\) cm. The percentage error in the calculated value of the volume is
Choose the correct statement about Zener diode:
If transistor having \(α = 0.9\), is used in CE configuration, then for a change of \(0.4\) mA in base current, what will be the change in collector current?
The threshold frequency of metal is \(f_0\). When the light of frequency \(2f_0\) is incident on the metal plate, the maximum velocity of photoelectron is \(v_1\). When the frequency of incident radiation is increased to \(5f_0\) the maximum velocity of photoelectrons emitted is \(v_2\). The ratio \(v_1\) to \(v_2\) is
The wavelength of the radiation emitted is \(λ_0\) when an electron jumps from the second excited state to the first excited state of hydrogen atom. If the electron jumps from the third excited state to the second orbit of the hydrogen atom, the wavelength of the radiation emitted will be \((20λ_0/x)\). The value of \(x\) is
An electron accelerated through a potential difference \(V_1\) has a de-Broglie wavelength of \(λ\). When the potential is changed to \(V_2\), its de-Broglie wavelength increases to \(2λ\). The value of \((V_1/V_2)\) is equal to
A pure silicon crystal at temperature \(300\) K has electron and hole concentration (\(n_i\)) \(10^{16}\) per m\(^3\) each and \(10^{21}\) phosphorus atoms (\(n_e\)) are added per cubic metre. The new hole concentration in silicon crystal is
An inductor of \(0.5\) mH, a capacitor of \(20\) \(μ\)F and resistance \(20\,\Omega\) are connected in series with a \(220\) V ac source. If the current is in phase with the emf, the amplitude of current of the circuit is \([x]^{1/2}\) A. The value of \(x\) is
In Young's double slit experiment, two slits \(S_1\) and \(S_2\) are 'd' distance apart and the separation from slits to screen is \(D\). Now if two transparent slabs of equal thickness \(0.1\) mm but refractive index \(1.51\) and \(1.55\) are introduced in the path of beam (\(λ = 4000\) Å) from \(S_1\) and \(S_2\) respectively. The central bright fringe spot will shift by ___ number of fringes.
When a beam of white light is allowed to pass through convex lens parallel to principle axis, the different colors of light converge at different point on the principle axis after refraction. This is called
'n' polarizing sheets are arranged such that each makes an angle \(45^{\circ}\) with the preceding sheet. An unpolarized light of intensity \(I\) is incident into this arrangement. The output intensity is found to be \(I/64\). The value of \(n\) will be
In a series LR circuit with \(X_L = R\). Power factor is \(P_1\). If a capacitor of capacitance \(C\) with \(X_c = X_L\) is added to the circuit the power factor becomes \(P_2\). The ratio of \(P_1\) to \(P_2\) will be :
A conducting loop of radius \(10/[π]^{1/2}\) cm is placed perpendicular to a uniform magnetic field \(0.5\) T. The magnetic field is decreased to zero in \(0.5\) s at a steady rate. The induced emf in the circular loop at \(0.25\) s is