Câu hỏi trắc nghiệm vật lý

What is the form of matter that exists around a charge created by that charge and characterizes the interaction between charges?

• Electric field.

• Electric potential.

• Electric charge.

• Electric potential energy.

The electric field intensity caused by a charge Q on a test charge q at a distance r is E. If the test charge q is replaced by a charge q' = -2q, what will happen to the electric field intensity at that point?

• Doubles in magnitude, direction same as E.

• Doubles in magnitude, direction opposite to E.

• Remains unchanged in magnitude, direction opposite to E.

• Remains unchanged in magnitude, direction same as E.

Two points M and N are on the same line of force of a uniform electric field with intensity E (MN↗↗E), the potential difference between M and N is UMN, and the distance MN = d. Which of the following formulas is incorrect?

• UMN=VM - VN.

• UMN=E.d.

• UMN=AMNq.

• UMN=qEd.

To charge a capacitor, one must

• Place the capacitor near a power source.

• Rub the capacitor plates together.

• Place the capacitor near a charged object.

• Connect a voltage across the capacitor.

A capacitor has capacitance C, charge Q, and voltage U. If the capacitor is disconnected from the source and the capacitance is reduced to half, what happens to the energy of the capacitor?

• Increases four times.

• Increases two times.

• Decreases by half.

• Remains unchanged.

Which statement is correct regarding the intensity of electric current in a metallic conductor?

• The intensity of electric current indicates the strength of the current.

• When the temperature increases, the intensity of electric current increases.

• The intensity of electric current through a circuit segment is inversely proportional to the charge moving through that segment.

• The current flows.

The resistance of a metallic conductor does not depend on

• the length of the conductor.

• the voltage applied across the conductor.

• the material of the conductor.

• the cross-section of the conductor.

The electromotive force of a power source is a quantity characteristic of its ability to

• exert force.

• do work.

• store electric charge.

• charge its two terminals.

The diagram shows some field lines of a system of two point charges. The correct statement is

• is a positive charge, is a negative charge.

• is a negative charge, is a positive charge.

• Both are positive charges.

• Both are negative charges.

A test charge q = 2.10^-5 C placed at point A in a uniform electric field experiences a force of 0.05 N. The electric field strength at point A is

• 2500 V/m.

• 10000 V/m.

• 4500 V/m.

• 7500 V/m.