Electric Fields

A positive charge is placed a short distance from a negative charge of equal magnitude. Which of the following diagrams best represents the electric field around the charges?

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Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

The electric field lines around two isolated point charges P and Q are illustrated in the given diagram. The field strength is zero at the point X.

Which statement must be true?

• Q is a smaller charge than P because X is closer to P than Q.

• Field strength is always proportional to the distance X.

• The potential at Q is less than the potential at P.

• The field lines show that both charges are positive

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

The given diagram shows a point charge situated at Y in front of an earthed metal sheet X. Two points P and Q are situated between X and Y and have electric field strengths E_P and E_Q respectively.

Which of the following expressions is correct?

• E_P = 0

• E_Q = 0

• E_Q > E_P

• E_P > E_Q

Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

In the definition of an electric field, reference is made to the force on a small test charge. Which of the following best explains why the test charge should be small?

• so that the test charge does not distort the electric field

• so that the force on the test charge is small

• so that the test charge does not create any forces on nearby charges

• so that Coulomb's law for point charges is obeyed

Tags

NGSS.HS-PS2-4

Which statement about an electric field strength is not correct?

• The electric field strength due to a point charge varies as 1/r² where r is the distance from the charge

• Electric field strength is a vector quantity

• The electric field strength at a point is a measure of the force exerted on a unit positive charge at that point

• The electric field strength is zero at all points where the potential is zero.

The given diagram shows two point charges -2Q and +Q situated a short distance apart. The resultant electric field due to the two charges is zero at one of the labelled points.

Which one of the points could it be?

• A

• B

• C

• D

Tags

NGSS.HS-PS2-4

The given diagram shows four point charges, each of magnitude Q, placed at three corners of a square.

Which of the given directions is that of the resultant electric field at the fourth corner?

• A

• B

• C

• D

Tags

NGSS.HS-PS3-5

The electric field strength and electric potential in the field of a point charge are determined at various distance r from the charge. Which of the following graphs correctly shows the variation with r of the electric field strength or the electric potential?

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Tags

NGSS.HS-PS2-4

NGSS.HS-PS3-5

A point charge experiences a force of repulsion F when situated at a distance x in air from another point charge. Which graph correctly shows how F varies with x?

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Tags

NGSS.HS-PS2-4

An ⍺ particle and a uranium nucleus are separated by a distance of 1.0 x 10^-13 m. The charge on an ⍺ particle is 3.2 x 10^-19 C and that on a uranium nucleus is 1.5 x 10^-17 C.

Which of the following is the electrostatic force between them?

• 4.3 x 10^-20 N

• 4.3 x 10^-13 N

• 4.3 N

• 4.3 x 10¹⁰ N

Tags

NGSS.HS-PS2-4