1. Which of the following is the SI unit of conductance?
1. Which of the following statements is false for a perfect conductor?
(a) The surface of the conductor is an equipoten-tial surface.
(b) The electric field just outside the surface of a conductor is perpendicular to the surface.
(c) The charge carried by a conductor is always uniformly distributed over the surface of the conductor.
(d) None of these.
Answer: d
2. Dielectric constant for a metal is
(a) zero
(b) infinite
(c) 1
(d) 10
Answer: b
3. When air is replaced by a dielectric medium of constant K, the maximum force of attraction between two charges separated by a distance
(a) increases K times
(b) remains unchanged
(c) decreases K times
(d) increases K-1 times
Answer: c
4. In a parallel plate capacitor, the capacity increases if
(a) area of the plate is decreased.
(b) distance between the plates increases.
(c) area of the plate is increased.
(d) dielectric constantly decreases.
Answer: c
5. A parallel plate air capacitor is charged to a potential difference of V volts. After disconnecting the charging battery the distance between the plates of the capacitor is increased using an insulating handle. As a result the potential difference between the plates
(a) increases
(b) decreases
(c) does not change
(d) becomes zero
Answer: a
6. Two identical capacitors are joined in parallel, charged to a potential V, separated and then connected in series, the positive plate of one is connected to the negative of the other. Which of the following is true?
(a) The charges on the free plated connected t mlo-gether are destroyed.
(b) The energy stored in ths system increases.
(c) The potential difference between the free plates is 2V.
(d) The potential difference remains constant.
Answer: c
7. A capacitor has some dielectric between its plates, and the capacitor is connected to a dc source. The battery is now disconnected and then the dielectric is removed, then
(a) capacitance will increase.
(b) energy stored will decrease.
(c) electric field will increase.
(d) voltage will decrease.
Aim : To study the charecteristics and verification of stability action of Zener diode
Apperatus : Zener diode, DC Battery , voltmeter
Miliammeter etc.
Formula : Static Resistance = V/I
Dynamic Resistance = ∆V/ ∆I
Diagram :
Procedure : 1) Make the connection as shown in circkt diagram. Here the Zener diode is connected in reverse biased mode.
2) Start increasing the voltage by 0.1V steps.
3) Note down the value of voltage where you first find the current in millimetre.
4) Go on increasing the value of Voltage from voltmeter. Note down the corresponding values of current. Note down the voltage at which current suddenly increases.
5) Draw a graph of Voltage Vs Current in third quadrant because the zener diode is connected in reverse biased mode.
6) Calculate the value of Resistance from the formula.
7) Interprete your Result with SI unit.
8) Write the conclusion from the observed
Results :
1) The Breakdown Voltage for Zener diode is......V
2) The calculated value of Static Resistance is.....ohm
3) The calculated value of Dynamic resistance is...ohm
Aim : To study the charecteristics of Silicon and Germanium diode and their comparison
Apperatus : pn junction diode of silicon and germanium.
Formula : Static Resistance = V/I
Dynamic Resistance = ∆V/ ∆I
Diagram :
Procedure : 1) Make the connection as shown in circkt diagram.
2) Start increasing the voltage by 0.1V steps.
3) Note down the value of voltage where you first find the current in millimetre.
4) Go on increasing the value of Voltage from voltmeter. Note down the corresponding values of current.
5) Draw a graph of Voltage Vs Current.
6) Calculate the value of Resistance from the formula.
7) Interprete your Result with SI unit.
8) Repeat the above steps 1) to 7) for second diode
9) Compare their Results and note that which diode is more conducive. Write the conclusion from the observed Results.
Result :
1) The Cut-in Voltage for Germanium and Silicon diodes are....... and.......
2) The calculated value of Static Resistance is.....
3) The calculated value of Dynamic resistance is....
ROM
