2005 - WAEC Physics Past Questions and Answers - page 5
41
Lenz's law of electromagnetic induction states that
A
a force is exerted on a current-carrying conductor in a magnetic field
B
electromotive force id induced in a circuit whenever there is a change in the magnetic flux linked with the circuit
C
the magnitude of the induced electromotive force in a circuit is proportional to the rate of change of flux linking the circuit
D
the induced current in a coil is in such a direction that it sets up a magnetic field which opposes the change producing it
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42
A bar magnet is placed near and lying along the axis of a solenoid connected to a galvanometer. The pointer of the galvanometer shows no deflection when
A
the magnet is moved away from the stationary solenoid
B
the solenoid is moved away from the stationary magnet
C
the magnet is moved towards the stationary solenoid
D
there is no relative motion between the magnet and the solenoid
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43
an electric motor is a machine that converts
A
mechanical energy into electrical energy
B
electrical energy into mechanical energy
C
high voltage to low voltage
D
low voltage to high voltage
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44
Which of the following statements is an advantage of nuclear fusion over nuclear fission?
A
The resulting chain reaction which produces large amount of energy
B
no radioactve wave is produced as bye product
C
very high temperature is required in the process
D
the end product is lead
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45
Which of the following statements is not a reason for using soft iron in making the core of a transformer? It
A
retains its magnetism for a long time
B
is easily magnitised
C
reduces energy loss due to hysteresis
D
is easily demagnetised
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46
Beta particles are faster-moving
A
protons
B
electrons
C
neutrons
D
photons
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47
A process by which two light atoms join to form a new atom of higher atomic mass is
A
natural radioactivity
B
nuclear fission
C
nuclear fusion
D
chain reaction
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48
Light of energy 5.0 eV falls on a metal of work function 3.0 eV and electrons are emitted, determine the stopping potential. [electronic charge, e = 1.60 x 108ms-19]
A
1.7V
B
2.0V
C
8.0V
D
15.0V
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49
The mass of a proton is 1.0089\(\mu\) and that of a neutron is 1.0089\(\mu\). Determine the energy evolved in stabilizing the nucleus of nitrogen of mass number 14 with 7 protons and 7 neutrons. [speed of light = 3.0 x 108ms-1; 1\(\mu\) = 1.67 x 10-27kg]
A
1.710 x 10-8J
B
3.131 x 10-8J
C
1.476 x 10-8J
D
2.332 x 10-9J
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50
Uranium of atom number 92 and mass number 238 emits an alpha particle from its nucleus. The new nucleus formed has respectively, atomic number and mass number
A
94 and 238
B
90 and 236
C
88 and 234
D
90 and 234
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