Electric Fields

A particle with mass moves in a horizontal straight line through a uniform electric field in a vacuum. The electric field is vertical.

There is a significant gravitational effect on the motion of the particle.

What could be the direction of the electric field and the sign of the charge, if any, on the particle?

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Which diagram best represents the field lines in the electric field produced by a combination of one point positive charge and one point negative charge?

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The diagram shows a thundercloud whose base is $500\ \text{m}$ above the ground.

The potential difference between the base of the cloud and the ground is $200\ \text{MV}$. A raindrop with a charge of $4.0 \times 10^{-12}\ \text{C}$ is in the region between the cloud and the ground.

What is the electrical force on the raindrop?

Options

A   $1.6 \times 10^{-6}\ \text{N}$
B   $8.0 \times 10^{-4}\ \text{N}$
C   $1.6 \times 10^{-3}\ \text{N}$
D   $0.40\ \text{N}$

A charged oil drop is held stationary between two charged parallel plates.

Which forces act on the oil drop?

Options

A   both electric and gravitational
B   electric only
C   gravitational only
D   neither electric nor gravitational

What is the electric field strength in a region where a proton accelerates at $2.00\ \text{m s}^{-2}$ due to the field?

Options

A   $11.4\ \text{pV m}^{-1}$
B   $5.22\ \text{nV m}^{-1}$
C   $10.4\ \text{nV m}^{-1}$
D   $20.9\ \text{nV m}^{-1}$

An oil drop of mass $2.6 \times 10^{-15}\ \text{kg}$ and with a charge of $-\ 4.8 \times 10^{-19}\ \text{C}$ is in a vacuum between two horizontal plates. The plates have a separation of $2.0\ \text{cm}$ and a potential difference (p.d.) between them of $1200\ \text{V}$, as shown.

Which statement describes the motion of the oil drop?

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A   It is stationary.
B   It has a downward acceleration of $9.7\ \text{m s}^{-2}$.
C   It has an upward acceleration of $1.3\ \text{m s}^{-2}$.
D   It has an upward acceleration of $11\ \text{m s}^{-2}$.

A charged particle is placed in a uniform field of force. The direction of the force on the particle is opposite to the direction of the field.

What is the field and what is the charge on the particle?

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A positively charged particle $P$ is in an electric field, as shown.

The field lines (lines of force) are evenly spaced and parallel.

Which statement is correct?

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A   Moving $P$ a small distance in any direction will not change the electric force on $P$.
B   Moving $P$ a small distance in direction $Y$ will increase the electric force on $P$.
C   Moving $P$ a small distance in direction $Z$ will increase the electric force on $P$.
D   Moving $P$ a small distance in direction $X$ will increase the electric force on $P$.

The diagram shows two parallel metal plates $P$ and $Q$, separated by a distance of $5.0\text{ mm}$. There is a potential difference of $700\text{ V}$ between the plates. Plate $Q$ is earthed.

What is the magnitude and direction of the electric field at point $R$?

Options

A   $1.4 \times 10^{2}\text{ N C}^{-1}$ from $P$ towards $Q$
B   $1.4 \times 10^{2}\text{ N C}^{-1}$ from $Q$ towards $P$
C   $1.4 \times 10^{5}\text{ N C}^{-1}$ from $P$ towards $Q$
D   $1.4 \times 10^{5}\text{ N C}^{-1}$ from $Q$ towards $P$

A particle has a charge of $+2.0\text{ mC}$ and is in a vertical uniform electric field. An electric force of $1.0 \times 10^{-2}\text{ N}$ acts upwards on the particle.

What is the electric field strength?

Options

A   $0.20\text{ V m}^{-1}$ downwards
B   $0.20\text{ V m}^{-1}$ upwards
C   $5.0\text{ V m}^{-1}$ downwards
D   $5.0\text{ V m}^{-1}$ upwards