Tag: physics

Answer is C.

The formula for quantisation of charge is given as q=ne.
where, q is the amount of charge in Coulumbs, n is the number of charges and e is the charge on the electron.
In this case, q=4/25 C
So, e = $1.6\times { 10 }^{ -19 }C$.
n can be calculated as n=q/e = $\frac { 4 }{ 25 } \times [\frac { 1 }{ 1.6\times { 10 }^{ -19 }C } ]\quad =\quad { 10 }^{ 18 }$ which is the number of electrons.
Hence, 4/25 Coulomb of charge contains ${ 10 }^{ 18 }$ electrons:.

The capacity of the metallic sphere is proportional to the radius. It does not matter whether it is solid or hollow. Therefore the hollow sphere will hold same charge as the solid sphere.

The word quantised means any quantity is an integral multiple of a minimum value and cannot have any value equal to decimal multiples.

Charge on a body is always $\displaystyle \pm e$, $\displaystyle \pm 2e$, $\displaystyle \pm 3e$. It can't be in fraction of e i.e 1.5e, 0.9e or -1.2e. The electronic charge is the minimum possible charge.

Charge on an electron is -e. SInce, an atom can lose or gain an integer number of electron, so charge on an will be an integer multiple of e.

Charge on a body is always $\displaystyle \pm e$, $\displaystyle \pm 2e$, $\displaystyle \pm 3e$. It can never be in fraction of e. i.e. 1.5e or -1.2e.

Since the charge is placed at the centre of the cube, so the electric flux lines move out equally from all sides of the cube. Thus the electric flux emerging from the cube is equal to $\dfrac{q}{\varepsilon _0}$.

Photon is the elementary quantum of energy.

Bulbs in street lightning are all connected in parallel.

For testing appliances, the wattage of test lamp should be high, as higher watt lamps have lower resistance and will not blow up the testing appliacnces.