In one of nasa's space tether experiments, a 20.0 km-long conducting wire was deployed by the space shuttle as it orbited at 7.86 ✕ 103 m/s around earth and across earth's magnetic field lines. the resulting motional emf was used as a power source. if the component of earth's magnetic field perpendicular to the tether was 1.38 ✕ 10−5 t, determine the maximum possible potential difference (in v) between the two ends of the tether.

Explanation:

It is given that,

Length of wire, l = 20 km = 20,000 m

Velocity around earth,

Earth's magnetic field,

Motional EMF is given by :

Where,

So, the maximum possible potential difference (in V) between the two ends of the tether is 1939.4 V. Hence, this is the required solution.

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form