Practice important
Relative Permittivity
MCQ questions and answers.
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MCQ Questions
1. Relative permittivity of a material is defined as the ratio of its permittivity to:
A.
The permittivity of vacuum
B.
The charge on the material
C.
The electric field in the material
D.
The capacitance of the material
Correct Answer:
The permittivity of vacuum
Explanation:
Relative permittivity is given by εr = ε/ε0, where ε is the permittivity of the material and ε0 is the permittivity of vacuum.
2. What is the relative permittivity of vacuum?
A.
0
B.
1
C.
8.85
D.
Infinite
Correct Answer:
1
Explanation:
The relative permittivity of vacuum is defined as ε0/ε0, which equals 1.
3. If a material has permittivity 4ε0, its relative permittivity is:
A.
ε0/4
B.
4
C.
1/4
D.
ε0 + 4
Correct Answer:
4
Explanation:
Using εr = ε/ε0, we get εr = 4ε0/ε0 = 4.
4. The relative permittivity of a material is also commonly called its:
A.
Dielectric constant
B.
Electric potential
C.
Charge density
D.
Electric flux
Correct Answer:
Dielectric constant
Explanation:
Relative permittivity is commonly known as the dielectric constant of the material.
5. Relative permittivity is a:
A.
Quantity with the unit coulomb
B.
Quantity with the unit farad
C.
Dimensionless quantity
D.
Quantity with the unit volt
Correct Answer:
Dimensionless quantity
Explanation:
Relative permittivity is a ratio of two permittivities, so their units cancel and it has no unit.
6. If the relative permittivity of an insulator is 6, its permittivity is:
A.
ε0/6
B.
6ε0
C.
ε0 + 6
D.
6/ε0
Correct Answer:
6ε0
Explanation:
From εr = ε/ε0, the permittivity is ε = εrε0 = 6ε0.
7. For an ordinary insulating material, relative permittivity is generally:
A.
Less than zero
B.
Equal to zero
C.
Greater than or equal to one
D.
Always infinite
Correct Answer:
Greater than or equal to one
Explanation:
For ordinary insulating materials, the permittivity is not less than that of vacuum, so relative permittivity is generally at least 1.
8. A material has relative permittivity 2. This means that its permittivity is:
A.
Half the permittivity of vacuum
B.
Equal to the permittivity of vacuum
C.
Twice the permittivity of vacuum
D.
Four times the permittivity of vacuum
Correct Answer:
Twice the permittivity of vacuum
Explanation:
A relative permittivity of 2 means ε/ε0 = 2, so ε = 2ε0.
9. Which expression correctly represents relative permittivity?
A.
ε0/ε
B.
ε + ε0
C.
ε − ε0
D.
ε/ε0
Correct Answer:
ε/ε0
Explanation:
Relative permittivity is defined as the ratio of the material's permittivity ε to the permittivity of vacuum ε0.
10. Two insulating materials have relative permittivities 3 and 5. Which material has greater permittivity?
A.
The material with relative permittivity 3
B.
The material with relative permittivity 5
C.
Both have the same permittivity
D.
Neither has permittivity
Correct Answer:
The material with relative permittivity 5
Explanation:
Since ε = εrε0, a larger relative permittivity corresponds to a larger absolute permittivity. Therefore, the material with εr = 5 has greater permittivity.