Physics - Study Mode

[#611] What is the minimum distance (in metres) required to hear an echo?
Correct Answer

(C) 17

Explanation

Solution: The velocity of sound in dry air is approximately 343 m/s at a temperature of 25 °C. Therefore, the reflecting object must be more than 17.2 m from the sound source for echo to be perceived by a person located at the source.

[#612] Sound travels fastest in
Correct Answer

(C) Glass

Explanation

Solution: Sound travels fastest in glass.

[#613] Which among the following determines the pitch of a sound?
Correct Answer

(B) Frequency

Explanation

Solution: Frequency is the number of occurrences of a repeating event per unit of time. It is also referred to as temporal frequency, which emphasizes the contrast to spatial frequency and angular frequency.

[#614] The fuse in an electric circuit is connected in
Correct Answer

(D) Series with live

Explanation

Solution: Fuses are always connected in series with the components to be protected from overcurrent, so that when the fuse blows (opens) it will open the entire circuit and stop current through the components.

[#615] Working of safety fuses depends upon 1. magnetic effect of the current 2. chemical effect of the current 3. magnitude of the current 4. heating effect of the current Select the correct answer using the code given below.
Correct Answer

(C) 3 and 4 only

Explanation

Solution: Working of safety fuses depends upon magnitude of the current and heating effect of the current.