Question

Pre-lab to Lab 4 - Charging, Discharging and Combination of Capacitors Name: Lab Section: 800ID#: 1) When a capacitor is connected to a battery, it gets fully charged: (1 point) a) Instantaneously b) After some time 't c) capacitor does not store charge 2) A capacitor of capacitance C = 1uF is connected to a resistor R = 100k. What is the time constant? (1 point) 3) At t-T RC, calculate the ratio 70 during discharging of a capacitor. Show your calculation. (Hint: Use equation 4) (2 points) 4) Four capacitors of 1 uF, 2 uF, 3 uF and 4uF are connected in series. What is the equivalent capacitance when connected in a) Series and b) Parallel? (1+1 = 2 points) 5) In figure 3, what does the flat line at the beginning of the graph represent? (1 point) 6) In figure 3, what physical quantity does the area under the curve represent? (1 point) 7) In figure 6(a), how will the equivalent capacitance change if the position of capacitors C. and C2 are switched? (1 point) 8) Capacitance of a capacitor (increases/decreases/remains same) when it is connected to a battery with higher voltage. (1 point)

Answer 1

1.(b)It takes some time to get fully charged.

2.time constant = R×C =100 × 10^3 × 1× 10^-6 =0.1 second

3. Q = Q_{​​​​​​0} e ^-t/RC

t =RC

Q / Q_{​​​​​​0}​​​​​ = e^{​​​​​​-1} = 0.3679

4.(a) capacitors in series

1/C = 1/C_{​​​​​​1} + 1/C_{​​​​​​2} + 1/C_{​​​​​​3} +1/C_{​​​​ 4} =1+(1/2)+(1/3)+(1/4)

1/C = 2.083

C = 0.48 $\mu$F

(b) in parallel ,C =C ₁+C ₂+C _{3 +}​​​_​​​​​​​C ₄ = 1+2+3+4 = 10 $\mu$F

5.Flat line indicates the maximum current when the capacitor is fully charged.