Apotential difference of 1.0 v was developed across a 10cm long thin metal bar as it moves through a magnetic field at 10m/s. the magnetic field is perpendicular to the velocity. what is the strength and direction of the magnetic field?

The correct option is: Option (D) 1.0T Out of the page.

Explanation:

The formula for the induced emf in the wire  = ε = Blv
ε = Potential difference = 1.0 V
v = speed of the wire = 10 m/s
l = length of the wire = 10cm  = 0.1 m
B = magnetic field = ?

Plug in the values:
B = ε/lv = 1/(0.1*10) = 1 T (And according to the right hand rule it should be out of the page.)

Uncle grandma

The rocks expand when there hot/warm  and contract when they are cold.