Lesson test: Charge and the electric field

1.[1p]
Electric charge is conserved: it is never created or destroyed, only moved from place to place.

True

Correct

False

The answer is: True

2.[2p]
In a metal wire the current direction is defined opposite to the actual motion of the electrons because

Franklin fixed the sign of charge before the electron was known, and the electron turned out negative

Correct

electrons move faster than the current

The answer is: Franklin fixed the sign of charge before the electron was known, and the electron turned out negative

the wire reverses the charge

The answer is: Franklin fixed the sign of charge before the electron was known, and the electron turned out negative

current is measured backwards on purpose

The answer is: Franklin fixed the sign of charge before the electron was known, and the electron turned out negative

3.[3p]
Two charges of $+ 2 \times 10^{- 6}$ C sit 5 cm apart. Using $k = 8.99 \times 10^{9}$ , what is the force between them, in newtons? Give it to one decimal place.

CorrectNot quite: 14.4

4.[2p]
Coulomb's law says the force between two charges falls off as

the square of the distance between them

Correct

the distance between them

The answer is: the square of the distance between them

the cube of the distance

The answer is: the square of the distance between them

the square root of the distance

The answer is: the square of the distance between them

5.[2p]
The electric field at a point is defined as

the force per unit charge a small test charge would feel there

Correct

the total charge at that point

The answer is: the force per unit charge a small test charge would feel there

the distance to the nearest charge

The answer is: the force per unit charge a small test charge would feel there

the energy stored there

The answer is: the force per unit charge a small test charge would feel there

6.[2p]
A metal conducts and a plastic does not because

a metal has electrons free to roam, while an insulator holds every electron tightly

Correct

a metal has more atoms

The answer is: a metal has electrons free to roam, while an insulator holds every electron tightly

a plastic has no charge

The answer is: a metal has electrons free to roam, while an insulator holds every electron tightly

a metal is heavier

The answer is: a metal has electrons free to roam, while an insulator holds every electron tightly

7.[1p]
Charge is quantised, always a whole-number multiple of the electron's charge.

True

Correct

False

The answer is: True

1.[1p] Electric charge is conserved: it is never created or destroyed, only moved from place to place.

2.[2p] In a metal wire the current direction is defined opposite to the actual motion of the electrons because

3.[3p] Two charges of +2×10-6 C sit 5 cm apart. Using k=8.99×109, what is the force between them, in newtons? Give it to one decimal place.

4.[2p] Coulomb's law says the force between two charges falls off as

5.[2p] The electric field at a point is defined as

6.[2p] A metal conducts and a plastic does not because

7.[1p] Charge is quantised, always a whole-number multiple of the electron's charge.

1.[1p]
Electric charge is conserved: it is never created or destroyed, only moved from place to place.

2.[2p]
In a metal wire the current direction is defined opposite to the actual motion of the electrons because

3.[3p]
Two charges of $+ 2 \times 10^{- 6}$ C sit 5 cm apart. Using $k = 8.99 \times 10^{9}$ , what is the force between them, in newtons? Give it to one decimal place.

4.[2p]
Coulomb's law says the force between two charges falls off as

5.[2p]
The electric field at a point is defined as

6.[2p]
A metal conducts and a plastic does not because

7.[1p]
Charge is quantised, always a whole-number multiple of the electron's charge.