IGCSE Physics Paper-1: Specimen Questions with Answers 135 - 138 of 149
Question number: 135
Question
The diagram shows a 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
Total wavelengths = + 1+
=
=
=
Question number: 136
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
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
Question
The circuit shown contains three 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