Wave speed = frequency * wavelength
Input the numbers into this equation :
Wave speed = 200 * 3
Work it out and you will get the answer :
Wave speed = 600 m/s
2 min = 120 sec
120/15 = 8
The black horse represents 8 seconds.
Since everything in the circuit is in series .. .
-- The total resistance is (3 + 2) = 5 ohms.
-- The voltage across the 3-ohm resistor is 3/5 of the total voltage.
-- The voltage across the 2-ohm resistor is 2/5 of the total voltage.
(2/5) of (9 volts) = 18/5 = 3.6 volts .