Physics - Study Mode

[#246] Q = mcdT refers to
Correct Answer

(C) Specific Heat formula

Explanation

Solution: Q = mcdT refers to Specific Heat formula.

[#247] Steam at 100°C causes more severe burns than water at 100°C because
Correct Answer

(B) Steam has latent heat of vaporisation

Explanation

Solution: Steam will produce more severe burns than boiling of water because steam has more heat energy than water due to its latent heat of vaporisation and additionally latent heat of condensation.

[#248] No current will flow between two charged bodies if they have the same
Correct Answer

(C) Potential

Explanation

Solution: There is no current flows between two charged bodies connected together when they have the same potential. For the flow of current between two conductors is that there must be a potential difference. Only then the electrons can flow from a higher potential to a lower potential.

[#249] Two metallic wires made from copper have same length but the radius of wire 1 is half of that of wire 2. The resistance of wire 1 is R. If both the wires are joined together in series, the total resistance becomes
Correct Answer

(C) 5R/4

Explanation

Solution: So, resistance of Wire 2 is R/4 as radius is half of wire 1, so area would be 4 times of wire 1. Now for resistance in series. R= R1 + R2. Therefore, Final R= R + R/4 = 5R/4

[#250] Find the resistance (in mega) of a wire of length 20m, cross sectional area 1 cm 2 and made of a material of resistivity 200m.
Correct Answer

(A) 40