Answer:
Explanation:
Given that,
A portable music player is operating with 4 cell batteries connected in series, and each cell has a P.D of 1.5V.
Then,
Total potential difference is
P.D_total = V1 + V2 + V3 + V4
P.D_total = 1.5 + 1.5 + 1.5 + 1.4
P.D_total = 6V.
The music player provides a resistance of 15,000Ω
R = 15,000Ω
We want to find the current (I) flowing through the music player?
Using ohms law
V = IR
Where
V is the potential difference
I is the current
R is the resistance
Therefore,
I = V/R
I = 6 / 15,000
I = 4 × 10^-4 A
I = 0.4 × 10^-3 A
I = 0.4 mA.
So, 0.4mA is passing through the music player

Explanation:
Natural length of a spring is
. The spring is streched by
. The resultant energy of the spring is
.
The potential energy of an ideal spring with spring constant
and elongation
is given by
.
So, in the current problem, the natural length of the spring is not required to find the spring constant
.

∴ The spring constant of the spring = 
Answer:
The speed of the wave with a frequency 100 mhz will be 
Explanation:
We have given that frequency of light is 100 mhz
We have to find the speed of light in vaccuum
We know that all electromagnetic waves travels in vaccum wth the same speed as the speed of light
And we know that speed of light is equal to 
So the speed of the wave with a frequency 100 mhz will be 
Всяко действие има равно по големина и противоположно по посока противодействие.