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10 resistors, each of resistance $R$ are connected in series to a battery of emf $E$ and negligible internal resistance. Then those are connected in parallel to the same battery, the current is increased $n$ times. The value of $n$ is
An electric dipole is placed as shown in the figure. The electric potential (in $10^2$ V) at point $P$ due to the dipole is ($\epsilon_0$ = permittivity of free space and $\frac{1}{4\pi\epsilon_0} = K$)
The area of a rectangular field (in $m^2$) of length 55.3 m and breadth 25 m after rounding off to the value for correct significant digits is:
Two bodies of mass $m$ and $9m$ are placed at a distance $R$. The gravitational potential on the line joining the bodies where the gravitational field equals zero, will be ($G = \text{gravitational constant}$)
The equivalent capacitance of the system shown in the following circuit is
In hydrogen spectrum, the shortest wavelength in the Balmer series is $\lambda$. The shortest wavelength in the Bracket series is
A bullet from a gun is fired on a rectangular wooden block with velocity $u$. When bullet travels $24$ cm through the block along its length horizontally, velocity of bullet becomes $\frac{u}{3}$. Then it further penetrates into the block in the same direction before coming to rest exactly at the other end of the block. The total length of the block is
In the figure shown here, what is the equivalent focal length of the combination of lenses (Assume that all layers are thin)? $n_1 = 1.5$, $n_2 = 1.6$, $R_1 = R_2 = 20$ cm
If the nucleus $^{27}_{13}\mathrm{Al}$ has a nuclear radius of about 3.6 fermis, then $^{125}_{52}\mathrm{Te}$ would have its radius approximately as:
$4.0 \text{ g}$ of a gas occupies $22.4 \text{ L}$ at NTP. The specific heat capacity of the gas at constant volume is $5.0 \text{ J K}^{-1}\text{mol}^{-1}$. If the speed of sound in this gas at NTP is $952 \text{ ms}^{-1}$, then the heat capacity at constant pressure is: (Take gas constant $R = 8.3 \text{ J K}^{-1}\text{mol}^{-1}$)
A 12 V, 60 W lamp is connected to the secondary of a step-down transformer, whose primary is connected to AC mains of 220 V. Assuming the transformer to be ideal, what is the current in the primary winding?
An alpha nucleus of energy 1/2 mv² bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to
The output ($Y$) of the given logic gate is similar to the output of an/a:
The ionisation energy of hydrogen atom is 13.6 eV, the ionisation energy of helium atom would be:
An ionised H-molecule consists of an electron and two protons. The protons are separated by a small distance of the order of angstrom. In the ground state: (a) the electron would not move in circular orbits. (b) the energy would be 2⁴ times that of a H-atom. (c) the electron's orbit would go around the protons. (d) the molecule will soon decay in a proton and a H-atom. Choose the correct option:
In terms of Bohr radius a₀, the radius of the second Bohr orbit of a hydrogen atom is given by
The variation of EMF with time for four types of generators is shown in the figures. Which amongst them can be called AC voltage?
An inductor of inductance L, a capacitor of capacitance C and a resistor of resistance R are connected in series to an AC source of potential difference V volts. The potential difference across L, C and R is 40 V, 10 V and 40 V, respectively. The amplitude of the current flowing through the LCR series circuit is $10\sqrt{2}$ A. The impedance of the circuit will be:
If $Z_1$ and $Z_2$ are the impedances of the given circuits (a) and (b) as shown in the figures, then choose the correct option:
A roller coaster is designed such that riders experience "weightlessness" as they go around the top of a hill whose radius of curvature is $20 \text{ m}$. The speed of the car at the top of the hill is between: