The variation of EMF with time for four types of generators is shown in the figures. Which amongst them can be called AC voltage?

(a)	(b)
(c)	(d)

The radius of the first permitted Bohr orbit for the electron in a hydrogen atom is 0.5 Å, and its ground state energy is \(-13.6~\text{eV}.\) If the electron in the hydrogen atom is replaced by a muon \((\mu^{-}),\) which has the same charge as the electron but is \(207\) times more massive, what will be the new values for the first Bohr radius and ground state energy?

The reading of an ideal voltmeter in the circuit shown is:

The metre bridge shown is in a balanced position with \(\frac{P}{Q} = \frac{l_1}{l_2}\). If we now interchange the position of the galvanometer and the cell, will the bridge work? If yes, what will be the balanced condition?

The relation amongst the three elements of Earth's magnetic field, namely horizontal component H, vertical component V and dip angle$$ $\delta$ is: ($B_E$=total magnetic field):

1. V=$B_E$tan$\delta$, H=$B_E$

2. V=$B_E$sin$\delta$, H=$B_E$cos$\delta$

3. V=$B_E$cos$\delta$, H=$B_E$sin $\delta$

4. V=$B_E$, H=$B_E$tan$\delta$ 

The rate of radioactive disintegration at an instant for a radioactive sample of half-life 2.2 $\times {10}^{9}s$ $is$ ${10}^{10}$ $s^{-1}$. The number of radioactive atoms in that sample at that instant is:

1. 3.7$\times {10}^{20}$

2. 3.17$\times {10}^{17}$

3. 3.17$\times {10}^{18}$

4. 3.17$\times {10}^{19}$

A circuit when connected to an AC source of \(12~\text{V}\) gives a current of \(0.2~\text{A}\). The same circuit when connected to a DC source of \(12~\text{V}\), gives a current of \(0.4~\text{A}\). The circuit is:

A cycle wheel of radius \(0.5\) m is rotated with a constant angular velocity of \(10\) rad/s in a region of a magnetic field of \(0.1\) T which is perpendicular to the plane of the wheel. The EMF generated between its centre and the rim is: