PHY407 Tma Solutions
1. A charge of 100micro F is placed on a parallel plate capacitor without dielectric , if paper with a dielectric constant of 1.5 is inserted between the parallel plate capacitor as dielctric . Calculate the amount of charge and the capacitance of the capacitor, if the potential difference between the end of the capacitor is 100 V
66.67 micro C , 0.67 micro Farad
66.67 micro C , 67 micro Farad
—>> 150 micro C , 1.5micro Farad
150 micro C , 0.015 micro Farad
2. A conductor is a material which has ___
Strongly bound electrons that cannot be detached from the atom
—>> Free moving electron that moves in the prescence of electric field
Material that does not allow electric current to flow through it
Strongly bound electrons that can only move under certain conditions
3. Polarization is defined as ____
—>> Dipole moment per unit volume
The rate of dipole moment
The ratio of charge qn and the position vector rn
The sum of the dipole moment and the electric field
4. When a dielectric is placed within the plates of a parallel capacitor ___
—>> The capacitance increase by a factor of the dielectric constant
The potential difference increase by a factor of the dielectric constant
The amount of charge reduce by a factor of the dielectric constant
The electric field increase by a factor of the dielectric constant
5. A parallel plate capacitor without dielectric has an electrc field of 100 V/m calculate the energy density of the capacitor taking the permittivity of free space to be 8.85*10-12
—>> 4.425E-8 FV2/m3
5000 FV2/m3
8.85E-8 FV2/m3
4.425E-10 FV2/m3
6. A parallel plate capacitor with polystyrene as dielectric has a capacitance of 480 μF calculate the capacitance of the same capacitor when the polystyrene with dielectric constant 2.4 is removed
1152 Îœf
5 nF
—>> 200 micro F
477.6micro F
7. The depolarization field E1 ____
Act in the same direction as the electric field
—>> Act in a direction opposite to the applied electric field
Does not require a direction
Act in all directions
8. Calculate the energy density of a parallel plate capacitor with dielectric, having an electric field of 10 V/m, if the permittivity of the dielectric is 3.275*10-11 F/m
1.638E-10 FV2/m3
3.275E-9 FV2/M3
50FV2/m3
—>> 1.638E-9 FV2/m3
9. A parallel plate capacitor with original charge density 500 micro C/m2 has a dielectric with dielectric constant K = 3.7 within it, calculate the induced charge density
—>> 0.00036487 C/m2
0.00013514 C/m2
7.4 nC/m2
0.00185 C/m2
10. The macroscopic electric field is equal to ___
The applied electric field minus the electric field due to the charges
—>> The sum of the applied electric field and the electric field due to the charges
The ratio of the applied electric field to electric field due to the charges
The product of applied electric field and electric field due to the charges
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