List of practice Questions

In the given network, if \(V_A-V_C=8\,\text{V}\), the value of \(R\) is
A parallel plate capacitor is formed by two plates each of area \(30\pi\,\text{cm}^2\) separated by \(1\,\text{mm}\). A material of dielectric strength \(3.6\times10^7\,\text{V m}^{-1}\) is filled between the plates. If the maximum charge that can be stored in the capacitor without causing any dielectric breakdown is \(7\times10^{-6}\,\text{C}\), the value of dielectric constant of the material is
An electron beam has an aperture \(2\,\text{mm}^2\). A total of \(6.0\times10^{15}\) electrons pass through any perpendicular cross-sectional area per second. The current density of the beam is
When a forward bias is applied to a p-n junction diode, then (A) majority carrier current becomes zero. (B) potential barrier is raised. (C) width of the depletion layer reduces. (D) junction resistance increases. Choose the correct answer from the options given below:
The circuit has two oppositely connected ideal diodes in parallel. The current flowing in the circuit will be
For a cell or a battery, the emf is (A) equal to the potential difference between its terminals when terminals are not connected externally (B) less than the potential difference between its terminals when the cell/battery is being discharged (C) always greater than the potential difference between its terminals (D) less than the potential difference between its terminals when the cell/battery is being charged Choose the correct answer from the options given below:
The oscillating electric and magnetic field vectors of an electromagnetic wave are in
A p-n junction diode \((D)\) shown in the figure below can act as a rectifier. An alternating current source \((V)\) is connected in the circuit. The current \((I)\) in the resistor \((R)\) can be shown by which graph?
The kinetic energy of an electron in the ground level in hydrogen atom is \(K\) units. The values of potential energy and total energy, respectively, are
The source of electromagnetic waves can be
Arrange the following in the correct order as the angle of incidence in a denser medium is gradually increased. (A) The refracted ray bends away from the normal. (B) The refracted ray grazes along the surface of separation. (C) The light is totally reflected back into the denser medium. (D) The ray passes undeviated when incident normally. Choose the correct answer from the options given below:
A proton accelerated through a potential difference \(V\) has a de-Broglie wavelength \(\lambda\). On doubling the potential difference, the de-Broglie wavelength of the proton
The radius of curvature of the curved surface of a plano-convex lens is \(20\,\text{cm}\). If the refractive index of the material of the lens is \(1.5\), it will
A metal at very low temperature has magnetic permeability \(\mu = 0\). It is a perfect
A deuteron and an alpha particle with the same kinetic energy move in circular paths under the effect of the same magnetic field. The ratio of the radii \((r_d:r_\alpha)\) of their trajectories is
Taking Bohr's radius as \(r_0=53\,\text{pm}\), the ground state radius of \(Li^{2+}\) ion, on the basis of Bohr's model, will be about
Arrange the following media (characterised by their relative dielectric permittivities \((\varepsilon_r)\) and relative magnetic permeabilities \((\mu_r)\)) according to the velocity of an electromagnetic wave propagating in them in ascending order. (A) \(\varepsilon_r=4,\ \mu_r=400\) (B) \(\varepsilon_r=3,\ \mu_r=300\) (C) \(\varepsilon_r=4,\ \mu_r=250\) (D) \(\varepsilon_r=5,\ \mu_r=150\) Choose the correct answer from the options given below:
In a Young's double slit experiment using monochromatic light of wavelength \(\lambda\), the intensity of light at a point on the screen is \(I_0\), where the path difference between two interfering waves is \(\lambda\). The path difference between the interfering waves at a point on the screen where the intensity is \(\dfrac{I_0}{4}\) will be
Match List-I with List-II in the context of Young's Double Slit Experiment.
Choose the correct answer from the options given below:
As shown in the figure, \(P\) and \(Q\) are two coaxial conducting loops separated by some distance. When the switch \(S\) is closed, a clockwise current \(I_P\) flows in \(P\) (as seen by \(E\)) and an induced current \(I_{Q1}\) flows in \(Q\). The switch remains closed for a long time. When \(S\) is opened, a current \(I_{Q2}\) flows in \(Q\). Then the directions of \(I_{Q1}\) and \(I_{Q2}\) (as seen by \(E\)) are
When a magnet is inserted into a coil, the induced e.m.f. in the coil does not depend on
The ratio of maximum wavelength to minimum wavelength in Balmer series is
A parallel plate capacitor \((C)\) is connected to a battery as shown in the figure. Consider two cases: Case-I: Key \(k\) is kept closed and plates of the capacitor are moved apart using an insulating handle. Case-II: Initially key \(k\) is closed for a long time and then opened. Now, the plates of the capacitor are moved apart using an insulating handle.
Identify the correct statements among the following: (A) In Case-I, \(Q\) remains same but \(C\) changes. (B) In Case-II, \(V\) remains same but \(C\) changes. (C) In Case-I, \(V\) remains same and hence \(Q\) changes. (D) In Case-II, \(Q\) remains same and hence \(V\) changes. Choose the correct answer from the options given below:
A charge \(q\) coulomb is circulating in an orbit of radius \(r\) metres making \(n\) revolutions per second. The magnetic field (in N/A m) produced at the centre of the circle is
The value of \(R\) in the given circuit, so that there is no current flow in the \(10\,\Omega\) resistor, will be