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JEE Main 2005 — Physics Modern Physics
A photocell is illuminated by a small bright source placed 1 m away. When the same source of light is placed 21 m away, the number of electrons emitted by photo cathode would
Held on 30 Apr 2005 · Verified 6 Jul 2026.
decrease by a factor of 4
increase by a factor of 4
decrease by a factor of 2
increase by a factor of 2
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Two $4$ bits binary numbers, $A = 1101$ and $B = 1010$ are given in the inputs of a logic circuit shown in figure below. The output $(Y)$ will be: 
Two radioactive substances A and B of mass numbers $200$ and $212$ respectively, shows spontaneous $\alpha$-decay with same $Q$ value of $1$ MeV. The ratio of energies of $\alpha$-rays produced by A and B is ________.
Using Bohr's model, calculate the ratio of the magnetic fields generated due to the motion of the electrons in the $2^{\text{nd}}$ and $4^{\text{th}}$ orbits of hydrogen atom _______.
The de Broglie wavelength for an electron accelerated through the potential difference of $V_1$ volt is $\lambda_1$. When the potential difference is changed to $V_2$ volt, the associated de Broglie wavelength is increased by $50\%$. If $(V_1/V_2) = (9/\alpha)$, then the value of $\alpha$ is __________.
The output $Y$ for the given inputs $A$ and $B$ to the circuit is: 
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