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Victoria Secondary Prelim 2021 P1
Quiz by Jessica Lew
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The diagram shows a wire in the magnetic field between two poles of a magnet. The current in the wire repeatedly changes as shown on the graph. What is the effect on the wire?
The force on the wire alternates between one direction and the opposite direction.
The force on the wire is constant in size and direction
There is no force acting on the wire at any time
There is only a force on the wire when the current reverses
The diagram shows part of a magnetic relay. P is part of the core of the electromagnet. Q is part of an armature that is attracted to the core when a current flows through the coil. R is a stud that stops the armature from being attracted too strongly to P. Which row gives the most suitable materials for P, Q and R?
P(copper) Q( copper) R( iron)
P(copper) Q( copper) R( copper)
P(iron) Q( iron) R( copper)
P(iron) Q( iron) R( iron)
The diagram shows a wire in the magnetic field between two poles of a magnet. The current in the wire repeatedly changes as shown on the graph. What is the effect on the wire?
The diagram shows part of a magnetic relay. P is part of the core of the electromagnet. Q is part of an armature that is attracted to the core when a current flows through the coil. R is a stud that stops the armature from being attracted too strongly to P. Which row gives the most suitable materials for P, Q and R?
Two soft-iron pins are suspended from the North pole of a bar magnet. Which diagram shows how the pins are deflected?
Some electrical equipment is connected to a 240 V supply. It is kept inside a metal case which is not earthed. A strand of wire has become loose and touches the metal case as shown. Which statement about this situation is correct?
A mains circuit can safely supply a current of 40 A.A hair-dryer takes 2 A. It is connected to the circuit by a wire which can carry up to 5 A. Which of these fuses would be best to use in the plug fitted to the hair-dryer wire?
A machine that can produce cryptocurrencies such as Bitcoin is rated at 3000 W. Electrical energy costs 20 cents per unit. What is the electrical cost of running 1000 identical machines for 24 hours?
Two copper wires X and Y have the same volume. Wire Y is four times as long as wire X. What is the value of [resistance of wire Y /resistance of wire X ]?
Which diagram correctly shows the electric field between a positively charged metal sphere and an earthed metal plate?
A dolphin has a range of audible frequencies of 150 Hz to 150 kHz. Which range of frequencies can both humans and dolphins hear?
Which statement about a converging lens is not correct?
A ray of light passes through plastic to air at the angles shown. What is the refractive index of the plastic?
700 g of alcohol at – 25 °C and 500 g of water at 25 °C poured into an insulated container and mixed together. The specific heat capacities of alcohol and water are 2400 J kg-1 K-1 and 4200 J kg-1 K-1 respectively. You may assume negligible heat transfer to the container. What is the temperature of the mixture at thermal equilibrium?
Heat is supplied at the same rate to a solid copper block and molten copper of the same mass in identical containers. Why does the temperature of the solid copper block rise at a slower rate?
A thermocouple is set up with the cold junction in melting ice at 0 °C and the hot junction is placed in boiling water at 100 °C. The reading from the sensitive voltmeter is 14 mV. When the hot junction is placed in a container of liquid of unknown temperature while the cold junction remains in the melting ice at 0 °C, the reading of the sensitive voltmeter is – 9 mV. What is the temperature of the container of liquid?
Which of the physical properties cannot be used to design a thermometer?
Temperature is a measure of
In a vacuum flask, which of the following is most effective in preventing heat loss by radiation?
What is observed during Brownian motion?
The electrical power supplied to a motor is 3000 W. It is able to lift a 10 kg mass at a constant velocity of 20 m / s for 5 s. What is the efficiency of the motor?
No work is done when a body is moving at a constant velocity along a smooth horizontal surface. The reason is