2008 - WAEC Physics Past Questions and Answers - page 4
31
A negatively charged rod is held close to an uncharged metal ball on an insulating stand. The ball will
A
be negatively chargeed
B
be positively charged
C
have an excess negatively charges on the side nearest the rod
D
have an excess positively charges on the side nearest the rod
correct option: d
Users' Answers & Comments32
Two bodies each carrying a charge of 2.00 x 10-10C are 5cm apart. Calculate the magnitude of the force between the charges.[\(\frac{1}{4\pi \mathit{E}_o} = 9.00 \times 10^9 Nm^2C{-2}\)]
A
1.44 x 10-7N
B
7.20 x 10-9N
C
7.20 x 10-11N
D
1.44 x 1011N
correct option: a
f = \(\frac{1}{4 \pi \mathit{E}_o} \times \frac{Q^2}{r^2} = \frac{9 \times 10^9(2 \times 10^{-2})^2}{(0.05)^2}\)
= 1.44 x 10-2N
Users' Answers & Comments= 1.44 x 10-2N
33
If the charge on an object is measured as 4.0 x 10-18C, how many excess electrons does the object possess, given that the charge of an electron is 1.6 x 10-18C
A
18
B
19
C
25
D
37
34
Which of the following is a unit of the time rate of flow of electric charges?
A
coulomb
B
ampere
C
volt
D
watt
correct option: b
Users' Answers & Comments35
A wire 1.0m long and with cross-sectional area 2.0 x 10-7 m2 has a resistance of 0.1\(\Omega\). Calculate the electrical conductivity of the wire
A
2.0 x 107\(\Omega^{-1} m^{-1}\)
B
5.0 x 107\(\Omega^{-1} m^{-1}\)
C
2.0 x 108\(\Omega^{-1} m^{-1}\)
D
5.0 x 108\(\Omega^{-1} m^{-1}\)
correct option: b
K = \(\frac{1}{RA} = \frac{1}{0.1 \times 2 \times 10^{-7}} = 5 \times 10^7\)
Users' Answers & Comments36
Three capacitors each of capacitance 1.5\(\mu F\) are connected in series. The total capacitance in the circuit is
A
2.0 \(\mu F\)
B
1.5 \(\mu F\)
C
0.6 \(\mu F\)
D
0.5 \(\mu F\)
correct option: d
Users' Answers & Comments37
A voltmeter is a device that
A
draws high current
B
has a very low resistance
C
has a very high resistance
D
is able to measure both voltage and current
correct option: d
Users' Answers & Comments38
Which of the following actions will not increase the sensitivity of a moving coil galvanometer?
A
using a strong temporary magnet
B
increasing the area and number of turns of the coil
C
using a week hair spring
D
using a light pointer
correct option: d
Users' Answers & Comments39
Fleming's right hand rule is also called the
A
motor rule
B
dynamo rule
C
screw rule
D
thumb rule
correct option: b
Users' Answers & Comments40
A transformer is required to supply 12 Vrms to operate a toy train set from a 240 Vrms. If the number of turns in the in the secondary coil is 100, calculate the number of turns required in the primary coil
A
5
B
12
C
2000
D
2400
correct option: a
\(\frac{E_s}{E_p} = \frac{N_s}{N_p} = \frac{240}{12} \frac{100}{N_p}\)
Np = 5
Users' Answers & CommentsNp = 5