Answer the questions.[Phy-2M]

Question 12 Marks

Calculate the resistance of an electric bulb which allows a 10 A current when connected to a 220 V power source?

Answer

$I =10 A, V =220 V$
$R=\frac{V}{I} $
$=\frac{220}{10} $
$=22 \Omega$

Question 22 Marks

A wire of given material having length 1 and area of cross-section A has a resistance of $4 \Omega$. What would be the resistance of another wire of the same material having length $1 / 2$ and area of cross-section 2A?

Answer

For first wire
$R_1=\rho \frac{l}{A}=4 \Omega$
Now for the second wire
$\begin{array}{l}R_2=\rho \frac{l / 2}{2 A}=\frac{1}{4} \rho \frac{l}{A} \\R_2=\frac{1}{4} R_1 \\R_2=1 \Omega\end{array}$
The resistance of the new wire is $1 \Omega$

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Question 32 Marks

List four sources of magnetic field.

Answer

(1) Magnetic field around a magnet.
(2) Magnetic field around current carrying conductor.
(3) Magnetic field around a current carrying solenoid.
(4) Magnetic field around an electromagnet.

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Science Answer the questions.[Phy-2M]

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