Water is a really good conductor of sound so I would have to say that it would be to send the message underwater because a more dense medium produces a louder sound
Answer:
b. increasing the number of turns per unit length on the solenoid
e. increasing the current in the solenoid
Explanation:
As we know that energy density depends on the strength of the magnetic field. The magnetic field strength depends on the no of turns of the solenoid and the current passing through it. The greater the number of turns per unit length, greater the current passing through it, more stronger the magnetic field is. As
B = μ₀nI
n = no of turns
I = current through the wire
So the right options are
b. increasing the number of turns per unit length on the solenoid
e. increasing the current in the solenoid
Answer:
Kinetic energy is maximum when the player hits the ball.
Explanation:
Kinetic energy 
, where m is the mass and v is the velocity.
So kinetic energy is proportional to square of velocity.
Velocity is maximum when the player hits the ball.
So kinetic energy is maximum when the player hits the ball.
<h2>The increase in length = 1.87 x 10⁻²</h2>
Explanation:
When copper rod is heated , its length increases
The increase in length can be found by the relation
L = L₀ ( 1 + α ΔT )
here L is the increased length and L₀ is the original length
α is the coefficient of linear expansion and ΔT is the increase in temperature .
The increase in length = L - L₀ = L₀ x α ΔT
Substituting all these value
Increase in length = 27.5 x 1.7 x 10⁻⁵ x 35.9
= 1.87 x 10⁻² m
