Solve each problem. Be sure to show your work and give a final answer with units rounded to the given number of significant figures.

1) Find the voltage on a circuit with a resistance of 12.5 Ω if it has a current of 2.35 A.

2) If a circuit with a 9.0 V battery has a current of 6.2 A, how much resistance is in the circuit?

3) A circuit has three resistors with values of 4.0 Ω, 8.0 Ω, and 12 Ω. What is the equivalent resistance if they are wired in series?

4) A circuit has three resistors with values of 4.0 Ω, 8.0 Ω, and 12 Ω. What is the equivalent resistance if they are wired in parallel?

1. the voltage will be 2.35×12.5 = 29.4V

2. the resistance would be 9.0/6.2= 1.45ohms

3. in series they will add up thus 4+8+12= 24ohms

4. in parallel it will be 2.18ohms

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y