1) A convergent lens has a focal length of 7cm. A 2cm tall image forms 30cm from

ID: 1313615 • Letter: 1

Question

1) A convergent lens has a focal length of 7cm. A 2cm tall image forms 30cm from the lens.

a)How far from the lens is the object?

b)What is the magnification?

c) What is the height of the object?

2) The intensity of sunlight impinging on the Earth is about 1.4 kW/m^2. What is the power emitted by the Sun? (Earth-Sun distance = 1.5 x 10^11m)

3) A very long wire generates a magnetic field of 0.0050 x 10 ^-4 T at a distance of 0.003m. What is the magnitude of the current?

4) An ideal gas is in a closed container. If its pressure is 133 Pa initially, and its temperature is 20.0

Number 1)

Part A)

Apply 1/f = 1/p + 1/q

1/7 = 1/p + 1/30

p = 9.13 cm

Part B)

M = -q/p

M = -30/9.13

M = -3.29 (Negative means inverted)

Part C)

h'/h = M

3.29 = h'/2

h' = 6.57 cm

Number 2)

P = IA

P = (1400)(4pi)(1.5 X 1011)

P = 2.64 X 1015 Watts which is 2.64 X 1012 kW

Number 3)

B = uI/2pir

.005 X 10-4 = (4pi X 10-7)(I)/(2pi)(.003)

I = .0075 Amps (which is 7.5 mA)

Number 4)

P/T = P/T (T is in Kelvin)

133/(293) = P/(333)

P = 151.2 Pa

Number 5)

P = F/A

(1 X 105 - .5 X 105) = F/(.2)(.4)

F = 4000 N

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