The mean free path \(l\) for a gas molecule depends upon the diameter, \(d\) of the molecule as:

An n-p-n transistor is connected in a common emitter configuration (see figure) in which collector voltage drop across load resistance ( 800 $\Omega$ ) connected to the collector circuit is 0.8 V. The collector current is: 

1.  2 mA 

2.  0.1 mA 

3.  1 mA 

4.  0.2 mA 

A person sitting on the ground floor of a building notices through the window, of height \(1.5~\text{m}\), a ball dropped from the roof of the building crosses the window in \(0.1~\text{s}\). What is the velocity of the ball when it is at the topmost point of the window? \(\left(g = 10~\text{m/s}^2\right )\)

The magnetic field in a plane electromagnetic wave is given by:
\(B_y = 2\times10^{-7} ~\text{sin}\left(\pi \times10^{3}x+3\pi\times10^{11}t\right )\text{T}\)${}_{}$
The wavelength is:
1. \(\pi\times 10^{3}~\text{m}\)
2. \(2\times10^{-3}~\text{m}\)
3. \(2\times10^{3}~\text{m}\)
4. \(\pi\times 10^{-3}~\text{m}\)

The length of the string of a musical instrument is \(90\) cm and has a fundamental frequency of \(120\) Hz. Where should it be pressed to produce a fundamental frequency of \(180\) Hz? 

The acceleration of an electron due to the mutual attraction between the electron and a proton when they are \(1.6~\mathring{A}\) apart is:
\(\left(\dfrac{1}{4 \pi \varepsilon_0}=9 \times 10^9~ \text{Nm}^2 \text{C}^{-2}\right)\)
1. \( 10^{24} ~\text{m/s}^2\)
2. \( 10^{23} ~\text{m/s}^2\)
3. \( 10^{22}~\text{m/s}^2\)
4. \( 10^{25} ~\text{m/s}^2\)

Which among the following verified the wave nature of electrons experimentally?

1. De-Broglie 

2. Hertz

3. Einstein 

4. Davisson and Germer 

Two solid conductors are made up of the same material and have the same length and the same resistance. One of them has a circular cross-section of area \(  𝐴 _1\) and the other one has a square cross-section of area \(A_2.\) The ratio of \(𝐴 _1 / 𝐴 _2  \) is:
1. \(1.5\)
2. \(1\)
3. \(0.8\)
4. \(2\)

For the circuit given below, Kirchhoff's loop rule for the loop \(BCDEB\) is given by the equation: