Answer:
The total voltage of the circuit is 18 volts.
Explanation:
We have, three identical resistors of resistance 3 ohms are connected in series in a circuit.
For a series combination, the equivalent resistance is given by the sum of individual resistances i.e.

Let V is the voltage of the battery if the current in the circuit is 2 A. So,


So, the total voltage of the circuit is 18 volts.
Gamma rays, X-rays, most ultraviolet rays, and some infrared are absorbed by the atmosphere but do not reach the Earth's surface
Answer:

Explanation:
Initial potential energy of the given spacecraft is given as

so we have

so we have






now total work done to move it to infinite is given
W = 0 - U

Answer:
1497×10⁵ km
Explanation:
Speed of light in vacuum = 3×10⁵ km/s
Time taken by the light of the Sun to reach the Earth = 8 min and 19 s
Converting to seconds we get
8×60+19 = 499 seconds
Distance = Speed × Time

1 AU = 1497×10⁵ km
The Sun is 1497×10⁵ km from Earth
Halflife is the time taken by a radioactive substance by half its original mass. In this case the half life of the substance is 3 hours.
Therefore; New mass = Original mass × (1/2)^n where n is the number of half lives. In this case, the half life is 3 hours and therefore; the number of half lives in 6 hours will be two.
= if the original mass is 100%
new mass = 100 × (1/2)^2
= 100 × 1/4 = 25%
The remaining mass will be 1/4 of the original mass, meaning a fraction of 3/4 of the initial mass will have decayed.
Thus; the answer is 3/4