Which quantity is measured in farad as the nature and behaviors of electrical quantities are considered?
A.Reactance
B.Inductance
C.Impedance
D.Capacitance
E.Resistance.
Sehemu B
2.6 alamas
(a)
Draw an electrical symbol of an air cored transformer.
2 alama
(a)
Draw an electrical symbol of an air cored transformer.
1 alama
(b)
Calculate the efficiency of a transformer for a single phase transformer with an input and output power of 2 kW and 1.9 kW respectively.
3 alama
(b)
Calculate the efficiency of a transformer for a single phase transformer with an input and output power of 2 kW and 1.9 kW respectively.
4 alama
Boresha ili kuona majibu ya mfano.
3.6 alamas
A moving coil instrument gives full-scale deflection with 15 mA and has a resistance of 5 Ω. Calculate the resistance required to enable the instrument to read up to:
(a)
1 A in parallel connection.
3 alama
(a)
Calculate the resistance required to enable the instrument to read up to 1 A in parallel connection.
3 alama
(b)
Calculate the resistance required to enable the instrument to read up to 10 V in series connection.
3 alama
(b)
10 V in series connection.
3 alama
Boresha ili kuona majibu ya mfano.
4.5 alamas
Calculate the supply voltage necessary for charging a battery of 110 cells at 30 A at the beginning and at the end of the charge. Each cell possesses a p.d of 2.1 volts at the beginning and 2 volts at the end of charge. Allow 0.06 Ω for the resistance of the connecting leads.
(none)
What is the required supply voltage range?
1 alama
Boresha ili kuona majibu ya mfano.
5.6 alamas
Study the circuit shown in the following circuit and answer the questions that follow.
(a)
Find the value of $I$ and $I_1$.
3 alama
(a)
Find the value of I₁ and I₂.
3 alama
(b)
Calculate the total current I.
2 alama
(b)
Calculate the total current $I$.
3 alama
Boresha ili kuona majibu ya mfano.
6.6 alamas
A lamp rated 230 V gives an illumination of 6000 lux and it takes 1.5 A from the mains. Calculate:
(a)
Calculate the efficiency of the lamp.
2 alama
(a)
Efficiency of the lamp.
3 alama
(b)
Calculate the mean spherical candle power.
3 alama
(b)
Mean spherical candle power.
3 alama
Boresha ili kuona majibu ya mfano.
7.5 alamas
A 4 poles, long shunt compound generator supplies 100 A at a terminal voltage of 500 V. If the armature resistance is 0.02 Ω, series field resistance is 0.04 Ω, shunt field is 100 Ω and the brush drop is 2 V, find the generated E.M.F
(none)
Find the generated E.M.F
0 alama
Boresha ili kuona majibu ya mfano.
8.5 alamas
Find the efficiency of a water heater which heats 140 liters of water with a specific heat capacity of 4180J/kg/ºC from 10ºC to 60ºC in 3 hours, given that, the water is heated by a 3 kW heater element.
(none)
Find the efficiency of a water heater which heats 140 liters of water with a specific heat capacity of 4180J/kg/ºC from 10ºC to 60ºC in 3 hours, given that, the water is heated by a 3 kW heater element.
0 alama
Boresha ili kuona majibu ya mfano.
9.6 alamas
Given the equation of an alternating current flowing through a certain circuit which is given by, $I = 50 \sin(100\pi t)$. Determine:
(a)
the maximum value of current;
2 alama
(a)
Determine the maximum value of current.
2 alama
(b)
Determine the r.m.s value of current.
2 alama
(b)
the r.m.s value of current,
2 alama
(c)
Determine the frequency of the current.
2 alama
(c)
the frequency of the current
2 alama
Boresha ili kuona majibu ya mfano.
10.5 alamas
A current of 6 A flows through a coil of 400 turns which is wound over a ring
(a)
the magnetic field density;
0 alama
(none)
This question is incomplete as presented. It likely asks to calculate something related to the magnetic field or flux based on the given information (current, number of turns, and the fact it's wound over a ring).
5 alama
(b)
the flux density,
0 alama
(c)
the total flux.
0 alama
Boresha ili kuona majibu ya mfano.
Sehemu C
11.45 alamas
SECTION C ( 45 marks)
Answer any three (3) questions from this section
(a)
The resonant frequency.
3 alama
(a)
Briefly explain how each of the three major losses in A.C generator takes place
0 alama
(b)
The current at resonance
3 alama
(b)
Calculate the line current when three similar coil each having a resistance and inductance of 20 Ω and 0.05 H respectively, are connected in star to a three phase 50 Hz supply with 400 V between lines.
0 alama
(c)
The voltage across L and C at resonance then, comment on the voltage obtained.
6 alama
(d)
Q factor of a circuit.
3 alama
Boresha ili kuona majibu ya mfano.
12.45 alamas
A coil of resistance 100 Ω and inductance 100 µH is connected in series with a 100 pF capacitor. The circuit is connected to a 10 V variable frequency supply.
Calculate:
(a)
The resonant frequency.
0 alama
(a)
Draw the circuit diagram including the parameters provided.
3 alama
(b)
Calculate the following parameters:
(i) Current in each branch.
(ii) Impedance of the circuit.
(iii) Phase angle of the circuit.
9 alama
(b)
The current at resonance
0 alama
(c)
The voltage across L and C at resonance then, comment on the voltage obtained.
0 alama
(c)
What will happen to the circuit characteristics if R is removed?
3 alama
(d)
Q factor of a circuit.
0 alama
Boresha ili kuona majibu ya mfano.
13.45 alamas
An inductance (L) 0.0637 H is connected in parallel with 30 Ω resistor. The combination is supplied by 200 V of 60 Hz
(a)
Draw the circuit diagram including the parameters provided.
0 alama
(a)
What is the importance of insulation part of the cable?
5 alama
(b)
Each conductor of 3-core copper cable, 178 meters long has a cross sectional area of 15 mm^2. The cable supplies power to a 413-V, 3 phase motor of 22 kW output which works at a full load at 0.72 p.f lagging with an efficiency of 87 per cent. Calculate:
(i) The voltage required at the supply of the cable
(ii) The power loss in the cable.
10 alama
(b)
Calculate the following parameters:
0 alama
(c)
What will happen to the circuit characteristics if R is removed?
0 alama
Boresha ili kuona majibu ya mfano.
14.45 alamas
Each conductor of 3-core copper cable, 178 meters long has a cross sectional area of 15 mm^2 . The cable supplies power to a 413-V, 3 phase motor of 22 kW output which works at a full load at 0.72 p.f lagging with an efficiency of 87 per cent.
Calculate:
(a)
What is the importance of insulation part of the cable?
0 alama
