IGCSE Physics Paper-1: Specimen Questions with Answers 135 - 138 of 149

Question number: 135

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Question

The diagram shows a wave.

Image of Wave

Image of Wave

How many wavelengths are there between X and Y?

Choices

Choice (4)Response

a.

b.

c.

d.

1

Answer

a.

Explanation

Image of the Wave

Image of the Wave

Total wavelengths = + 1+

=

=

=

Question number: 136

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Question

What is the melting point of pure water?

Choices

Choice (4)Response

a.

b.

c.

d.

Answer

b.

Explanation

  • The temperature at which the substance or solid will get is known as melting point.

  • The melting point of pure water is

  • And at the temperature the liquid gets evaporate is known as boiling point.

  • The boiling point of pure water is

Question number: 137

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Question

Sodium-24 has half-life of 15 hours. If there are 1600g of Na-24 initially, how will it take for 1400g of Na-24 to decay?

Choices

Choice (4)Response

a.

45 hrs

b.

50 hrs

c.

1 day

d.

40 hrs

Answer

a.

Explanation

For finding half-life the formula is

In ( ) =-kt

Here,

K =

K = constant and = half life

K =

In ( ) =-kt

In ( )

In

t =

t = 45 hrs

(OR)

3 half-lives for sample to decay from 1600g to 200g

I. e.

45hours for 1400g of sodium-24 to decay

Question number: 138

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Question

The circuit shown contains three lamps and 4 switches

3 lamps and 4 switches

3 Lamps and 4 Switches

Which switches must be closed to light up lamp1 and lamp3?

Choices

Choice (4)Response

a.

switch 1,2, 3 and 4 only

b.

switch5 only

c.

switch1, switch2 and switch5 only

d.

switch1 and switch2 only

Answer

c.

Explanation

  • The given circuit is a parallel circuit. In a parallel circuit the current passes in a closed path.

  • If there is any breakage the current does not flows through it.

  • From the circuit, the switch1, switch2 and switch5 must be closed to light the lamp 3.

Image 3 lamps and 4 switches

Image 3 Lamps and 4 Switches

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