Answer: It's the third one.
Explanation:
Answer: True
Explanation:
A photo detector that can respond to the entire rang of visible light can be design, it is true.
Photo detector is a device in an optical receiver which receives optical signals and convert it to electric signal. It is the key device position in front of the optical receiver.
Answer:

Explanation:
<u>Dynamics</u>
When a particle of mass m is subject to a net force F, it moves at an acceleration given by

The particle has a mass of m=2.37 Kg and the force is horizontal with a variable magnitude given by

The variable acceleration is calculated by:


The instant velocity is the integral of the acceleration:


Integrating



Answer:
b) 252 Hz or 260 Hz
c) 0.25 s
Explanation:
b) The frequency of the beats is 4 Hz, and one tuning fork has a frequency of 256 Hz. Therefore, the second tuning fork is either 4 Hz lower or 4 Hz higher.
f = 252 Hz or 260 Hz
c) Period is the inverse of frequency.
T = 1/f
T = 1 / (4 Hz)
T = 0.25 s
Since they are rowing against the current, their velocity realtive to the groud is 20-1.5 = 18.5km/h
So the distance travelled is 18.5km/h*0.5h = 9.25km
Going back with the current their ground realative velocity is 20+1.5 = 21.5km/h so the time it takes them to return 9.25 km is 9.25km/(21.5km/h) = 0.43h ~= 26 min