Question

Hi,

Can you please solve these problems.

For the information below to answer Questions 1-5.

An electronic flashgun has a 2500 μF electrolytic capacitor charged to 300 V and a current-limiting 10 kΩ resistor and. If the lamp resistance is 10 Ω:
Question 1
Find the peak charging current
[2]
1) 30 A
2) 15 mA
3) 30 mA
4) 20 A
Question 2
Find the time required for the capacitor to fully charge (Hint: an electronic flash unit is like an RC circuit)
[2]
1) 25 s
2) 125 s
3) 12.5 s
4) 5 s
Question 3
Find the peak discharging current
[2]
1) 30 A
2) 0.3 A
3) 10 S
4) 3 A
8
Question 4
Find the total energy stored in the capacitor
[2]
1) 112.5 J
2) 125 J
3) 0.375 J
4) 37.5 J
Question 5

Find the average power dissipated by the lamp
[2]
1) 4 500 W
2) 45 WJ
3) 405 W
4) 900 W
Question 6
An office building uses 100 lights of 80 W each. If they leave the lights on all day and night, what is the electricity account after one month (30days)? Assume electricity costs R 1.5 per kWh.
[2]
1) R 8000
2) R 8640
3) R 12000
4) R 240000
Question 7
The charge through an element is constant at 2 mC between t=0 s and t=2 s. Between t=2 s and t=4 s, the charge falls linearly to 0 mC. What is the energy usage associated with the element if the potential difference across the element is 9 V?
[2]
1) -18 mJ
2) 18 mJ
3) 16 mJ
4) R 24 mJ
CAN4701/101/0/2019
9
Question 8
Calculate the charge represented by 3 million protons. Give your answer in pico-Coulomb (pC).
[2]
1) q = 48 pC
2) q = 4.8 pC
3) q = 0.48 pC
4) q = 24 pC

Question 9
Find the energy (in Joule) required to move 2C of charge through a 5Ω resistor in 3s.
[2]
1) W = 30 J
2) W = 6.67 J
3) W = 10 J
4) W = 6 J
Question 10
An electric motor can deliver 50 kJ in 2 minutes. Find the annual cost (in Rand) of running the motor if it is used for 5 hours a day, 300 days a year. The cost of electricity is R 1/kWh.
[2]
1) R 3000
2) R 15000
3) R 700
4) R 625

Answer 1