Science MCQ (1 Marks)

Shivam went for buying a $CFL$ from $D -$ mart,ISI safety mark he should look for $ISI$ mark is a certification mark for industrial products in India.
The mark certifies that a product confirms to the Indian Standard$(IS),$ mentioned as $CM/L-xxxxxxx$ on top of the mark, developed by the Bureau of Indian Standards $(BIS),$ the national standards body of India.

 A combination of two or more cells is called a battery.
The minimum number of cells require to make a battery is $2.$

 The given symbol is used for $AC$ source of electric current in an electric circuit.

1. Using a powerful electromagnet to make the magnetic field stronger in place of a permanent magnet.
2. By winding the coil round a soft iron core to increase the strength of magnetic field.
3. By using a coil with more turns.
4. By rotating the coil faster.
5. By using a coil with a larger area.

The electric bulb works by heating up a small wire called the filament.
Electric current heats the filament so much that it glows.
In fact, $90\%$ of the electricity used by a electric bulb is converted to heat and this conversion produces maximum wastage of electrical energy.

Fuse boxes contain safety devices called fuses or circuit breakers $- MCB$ (Miniature Circuit Breaker) which are designed to prevent an excess of electric current entering your house by only allowing a certain maximum current to flow in.
When the electrical current is too large, an electromagnet attracts a spring loaded switch which breaks the circuit and cuts the power supply.
The switch must be reset before any current can flow again.

Amount of heat produced in wire $= I^2R$
Where $R =$ Resistance of wire
$I =$ Current through wire
As resistance of wire $\text{R}\propto\frac{\text{L}}{\text{A}}$
So heat produced depends on Length as well as thickness.