We have that the electric field at the center of the metal ball due only to the charges on the surface of the metal ball is

From the question we are told that
A solid metal ball of radius 1.5 cm
bearing a charge of -15 nC is located near a hollow plastic ball of radius 1.9 cm bearing
uniformly distributed charge of -7 nC
The distance between the centers of the balls is 9 cm
Generally the equation for the electric field is mathematically given as


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i don't know the anss , sorry.
Answer:
im pretty sure it is 3.0 K
Explanation:
The first transistor made of gold, plastic and germanium was about the size of adult's fingernail.
Option C
<u>Explanation:</u>
The first transistor made of gold, plastic and germanium was invented in Bell laboratories. It is termed as point contact transistor. As it is made like a pointed arrow with both the sides covered with layer of gold foil. The germanium is used at the tip, just like the base and the gold foil ends as collector and emitter.
The size of this transistor is about the size of adult's fingernail. It is very small in size and it was one of its kind. Due to this small size and the working capacity by the point contact, it is termed as point contact transistor.
Answer:
some common devices that use current carrying conductors and magnetic fields are electric motor electric generator loudspeakers microphones and measuring instruments like galvanometer ammeter and voltmeter