Answer:


Explanation:
Wave 1, 
Wave 2, 
Wave 3, 
Wave 4, 
The general equation of travelling wave is given by :

The value of
will remain the same if we take phase difference into account.
For first wave,



For second wave,



For the third wave,



For the fourth wave,



It is clear from above calculations that waves 1 and 3 have same time period. Also, wave 2 and 4 have same time period. Hence, this is the required solution.
Answer:
he spring provides the controlling torque. The air friction induces the damping torque, which opposes the movement of the coil. The repulsion type instrument is a non-polarized instrument, i.e., free from the direction of current passes through it. Thus, it is used for both AC and DC
Answer:
75 W
Explanation:
= temperature of the filament = 2100 K
= Emitting area of the filament = 1 cm² = 10⁻⁴ m²
= Emissivity = 0.68
= Stefan's constant = 5.67 x 10⁻⁸ Wm⁻²K⁻⁴
Using Stefan's law, Power output of the light bulb is given as

Answer:
1.56 J
Explanation:
given,
Spring compression, x = 2.5 cm
Force exerts by the spring,
F = - k x
k = 5000 N/m
Potential energy stored = ?
energy stored in the spring


PE = 1.56 J
Hence, the potential energy stored in the car is equal to 1.56 J.