A-Level Physics Question Analysis Topic: Physics - Short Questions
Exam Questions:
1) A 10 V battery of negligible internal resistance is connected across a 200 V battery and a resistance of 38Ω as shown in the figure. Find the value of the current in circuit.
2) Write three important factors which justify the need of modulating a message signal. Show diagrammatically how an amplitude modulated wave is obtained when a modulating signal is superimposed on a carrier wave.
Answers:
For A-Level Physics, you should know:
1) From the above diagram, we can find:
The net potential difference that is being applied across the resistor is 200V - 10V = 190V.
We also know that the resistor has a resistance of 38Ω.
As such, the current going through the resistor is 190V / 38Ω = 5A.
2) Three important factors:
(a) The size of the aerial or antenna. In order to have communication, transmitting frequencies must be high.
(b) The effective power radiated from the antenna. High frequency signals are achieved by the help of modulation.
(c) Signals from different transmitters facing interference: To avoid such a problem, high frequency signals are needed (which can be achieved as mentioned in b)!
Work hard for your A-Level Physics examination!
End of analysis. Great!
