Answer:
The time is 106.7 minute.
Explanation:
Given that,
Density 
Current 
Diameter of wire = 1.2 mm
Length = 31 cm
We need to calculate the drift velocity
Using formula of drift velocity


Put the value into the formula


We need to calculate the time
Using formula for time


Where, l = length
= drift velocity
Put the value into the formula



Hence, The time is 106.7 minute.
It would be the temperature of the steel decreases and the temperature of the water increases
Answer
Given,
Length of the wire,L = 31 cm = 0.31 m
mass of the wire, m = 9 g = 0.009 Kg
Current in the wire,I = 7 A
Magnetic field strength, B= ?
Equating magnetic force to the weight of the wire.



B = 0.0407 T
For Force to be upward magnetic field direction should be outward of the plane of paper.
Answer:
D)
Explanation:
The Period-Luminosity relationship tells us that luminosity increases with the period, and of course the more luminosity a star has the more far away they can be seen, so from this we know that:
A) False since lower luminosities can be observed when they are close.
B) False since longer periods means higher luminosities
C) False since lower luminosities can be observed when they are close.
D) True: Variable stars with shorter periods have lower luminosities, so they can only be observed when they are close.
No don't feel feel like they do