Answer the questions.[Phy-2M]

Question 12 Marks

In the experiment to study the dependence of current $(\mathrm{I})$ on the potential difference $(\mathrm{V})$ across a resistor, a student obtained a graph as shown.
i. What does the graph depict about the dependence of current on the potential difference?
ii. Find the current that flows through the resistor when the potential difference across it is 2.5 V .

Answer

i. $\mathrm{V} \propto \mathrm{I}$ i.e current is directly proportional to applied voltage.
ii. at 2.5 V current will be 0.25 A

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Question 22 Marks

An electric heater rated 1100 W operates at 220 V . Calculate (i) its resistance, and (ii) the current drawn by it.

Answer

i. $\mathrm{P}=\frac{V \times V}{R}$
$\mathrm{R}=\frac{V \times V}{P}$
$\mathrm{R}=\frac{220 \times 220}{1100}$
$\mathrm{R}=\frac{48400}{1100}$
$\mathrm{R}=44 \mathrm{ohm}$
ii. $\frac{V}{I}=\mathrm{R}$
$\mathrm{I}=\frac{V}{R}$
$\mathrm{I}=\frac{220}{44}$

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Question 32 Marks

Draw a ray diagram showing the path of rays of light when it enters with oblique incidence:
a. from air to water
b. from water to air

Answer

a. From air to water : Since the light is going from rarer (air) to denser (water) medium, therefore it will bend away from normal after refraction.

b. From water to air : Since the light is going from denser (water) to rarer (air) medium, therefore it will bend towards normal after refraction.

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Science Answer the questions.[Phy-2M]

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