# Physics Questions

Q:

The most suitable unit for expressing nuclear radius is

 A) micro B) nanometre C) fermi D) angstrom

Explanation:

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Q:

The working principle of a washing machine is

 A) reverse osmosis B) diffusion C) centrifugation D) dialysis

Explanation:

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Q:

The speed of light will be minimum while passing through

 A) water B) vaccum C) air D) glass

Explanation:

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Q:

Nuclear sizes are expressed in a unit named

 A) Fermi B) Angstrom C) Newton D) Tesla

Explanation:

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Q:

Two electric bulbs marked 25W – 220V and 100W – 220V are connected in series to a 440Vsupply. Which of the bulbs will fuse?

 A) 25 W B) Both C) 100 W D) Neither

Explanation:

Resistances of both the bulbs are

$R_{1}=\frac{V^{2}}{P_{1}}=\frac{220^{2}}{25}$

$R_{2}=\frac{V^{2}}{P_{2}}=\frac{220^{2}}{100}$

Hence  $R_{1}>&space;R_{2}$

When connected in series, the voltages divide in them in the ratio of their resistances. The voltage of 440 V devides in such a way that voltage across 25 w bulb will be more than 220 V. Hence 25 w bulb will fuse.