Answer:

Explanation:
Given,
Magnetic field, B = 5 x 10⁻⁵ T
Number of turns, N = 450
length = 29 cm
Current,I = ?
Using formula of magnetic field due to solenoid




Hence, the current obtained is equal to 0.0256 A.
Answer:
12N to the right.
Explanation:
There is a force of 12N upwards and a force of 12N downwards: these cancel out.
Assign a negative value to forces towards the left, and a positive value to the forces towards the right: -3N and +15N
Combine them: -3N+15N = 12N
The net force has a magnitude of 12N, and since our answer was positive, it acts towards the right.
Answer:
5.03 m
Explanation:
The wavelength of a wave is given by

where
v is the speed of the wave
f is the frequency of the wave
For the sonar signal in this problem,


Substituting into the equation, we find the wavelength:

Answer:
The answer is B.
Explanation:
Given that the <em>current </em>(Ampere) in a series circuit is same so we can ignore it. We can assume that the total voltage is 60V and all the 3 resistance are different, 20Ω, 40Ω and 60Ω. So first, we have to find the total resistance by adding :
Total resistance = 20Ω + 40Ω + 60Ω
= 120Ω
Next, we have to find out that 1Ω is equal to how many voltage by dividing :
120Ω = 60V
1Ω = 60V ÷ 120
1Ω = 0.5V
Lastly, we have to calculate the voltage at R1 so we have to multiply by 20 (R1) :
1Ω = 0.5V
20Ω = 0.5V × 20
20Ω = 10V
..............no.......................