I believe it is the first one.
This is because of the Doppler Effect.
The Doppler Effect is when the frequency of the wave changes for an observer moving relative to the wave source.
Basically, as the police car moves away from you, the distance between you and the car increases, which makes the sound waves spread out.
Answer: hello your questions lacks the required resistor values therefore i will provide a general answer using an example
answer : a) 14 ohms b) 0.86 amps c) 10.32 V
Explanation:
Assuming the resistors are : 3 ohms , 4 ohms and 5 ohms
Voltage source = 12V
<u>Assuming that the Resistors are in series </u>
<u>a) Determine Total resistance </u>
Req = R1 + R2 + R3
= 3 + 4 + 5 = 14 ohms
<u>b) Total current </u>
Ieq = V / Req
= 12 / 14 = 0.86 amps
<u>c) The Total Voltage over the entire system </u>
Vt = ∑ Voltage drops
= ( 0.86 * 3 ) + ( 0.86 * 4 ) + ( 0.86 * 5 )
= 10.32 V
Given:
distance from the projector lens to the image, di
projector lens focal length, f
distance from the transparency to the projector lens, do
thin lens equation: 1/f = 1/di + 1/do
do = 4 inches
di = 8 feet
convert feet to inches, for uniformity.
1 foot = 12 inches
8 feet * 12 inches/ft = 96 inches
1/f = 1/96 inches + 1/4 inches
Adding fractions, denominator must be the same.
1/f = (1/96 * 1/1) + (1/4 * 24/24)
1/f = 1/96 + 24/96
1/f = 25/96
to find the value of f, do cross multiplication
1*96 = f * 25
96 = 25f
96/25 = f
3.84 = f
The focal length of the project lens is 3.84 inches
