Atransformer changes 120 v across the primary to 1200 v across the secondary. if the secondary coil has 800 turns, how many turns does the primary coil have?
(a) 40
(b) 80
(c) 100
(d) 400
(e) 4000

the answer is B 80turns

Explanation:

Hello!

Remember that a transformer is an electrical device that allows you to change the voltage and current levels keeping the electric power constant, in this order of ideas the equation that governs this device is as follows

where

Vp= primary voltage=120V

Vs= secondary voltage=1200V

Ns=turns of secondary=800

Np=turns of primary

now we solve for Np

the answer is B 80turns

explanation:

as the height from which the ruler was dropped increased, the speed of the ruler at ryan's hand increased.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s