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Secondary 1 Challenging Science Lesson 23: Worksheet Questions

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Lesson 23: Heat and Its Effects

Section A: Multiple-choice Questions Choose the correct answer and write its letter in the brackets provided. 1. The figure shows the electric power being transmitted to households by the transmission wires.

Which statement best explains why the transmission wires are hung loosely from pole to pole? A B C D To allow expansion of cables during hot day so that they will not break apart. To prevent the cables from breaking into pieces during cold winter. To prevent the loss of electricity during transmission. To make the maintenance of the transmission wires easily. ( B )

2.

Which of the following is not one of the solutions to reduce the undesirable thermal effect in its application? A B C D Gaps between railway lines. Expansion bends in water heater. Thermometer using a bimetallic strip. Cables loosely strung between poles. ( C )

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Secondary 1 Challenging Science Lesson 23: Worksheet Questions

3.

The diagram below shows the effect of heat on two different bimetallic strips.

Which of the following statements can be made about these two different bimetallic strips? A B C D Metal P has a greater length in a bimetallic made of metals P and R when heating. Metal Q would contract the most during cooling than metals P and R. Metal R would have a shorter length than metal Q during cooling. None of the above. ( C )

4.

Which of the following materials has the greatest expansion when they are heated from room temperature to 50° C? A C Liquid mercury Iron block B D Aluminium foil Helium gas

( D )

5.

Which of the following is not one of the applications of thermal effect? A B C D Thermostat in fire alarms Contraction of rivets Expansion bends in water pipes Fixing axle and wheel together ( D )

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Secondary 1 Challenging Science Lesson 23: Worksheet Questions

6.

Explain why there is a constriction in clinical thermometers. A B C D To allow mercury to expand uniformly in the clinical thermometers. The constriction measures temperature below 40 ° C. It prevents the mercury from flowing back quickly into the bulb. None of the above ( C )

7.

What thermometers can be used to measure both -100° and 1 500° C C? A B C D Resistance thermometer Thermocouple thermometer Liquid crystal thermometer It is impossible to measure such temperatures

( B )

8.

Which statements are correct? I II III IV A C Alcohol reacts faster to temperature changes as compared to mercury. Alcohol cannot measure high temperatures accurately. A large amount of liquid is needed for mercury or alcohol thermometers. Mercury is able to expand more evenly in thermometers. I and II I and IV B D II and IV I, II and IV

( B )

9.

How does a thermocouple work? A B C D Expansion and contraction of a liquid. Uneven expansion and contraction. Resistance of wire. Voltage different between two points of wires. ( D )

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Secondary 1 Challenging Science Lesson 23: Worksheet Questions

10.

Which of the following features enables a mercury-in-glass thermometer to respond quickly to changes in temperature? A B C D The bulb wall should be thin. The bulb should contain a lot of mercury. The bore should be narrow. The stem wall should be thin.

( A )

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Secondary 1 Challenging Science Lesson 23: Worksheet Questions

Section B: Structured Questions Write your answers in the spaces provided.

1.

The figure below shows an experiment set up which investigates the effect of cooling on two different liquids X and Y. Both liquids are at the same room temperature initially. The water level is indicated by the graduated glass tube.

Each liquid is placed in a beaker of water at 0° for 5 minutes. The C results of the experiment are shown in the Table below. Time(min) Liquid Level of X (mm3) Liquid Level of Y (mm3) (a) 0 25.0 25.0 1 25.4 25.4 2 25.1 25.2 3 24.6 24.9 4 24.2 24.6 5 23.4 24.2

What happens to both liquids X and Y when they are placed in the beaker of water of 0° after 5 minutes? C Both liquids contract.

(b)

Compare the effect of cooling on liquids X and Y based on the results obtained from 2 minutes to 5 minutes. Liquid X contracts more than liquid Y.

(c)

Explain the observation of the liquid level for both liquids X and Y from 0 to 2 minutes. Glass flask contracts first. As a result, its volume decreases and this pushes the liquid level up.

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Secondary 1 Challenging Science Lesson 23: Worksheet Questions

2.

Explain the following using the principle of expansion and contraction. (a) There are gaps present in different positions of a road. It allows the road to expand during hot weather so that the road can be prevented from cracking. (b) A metal bridge has one end that is fixed and the other end with metal rollers. Rollers are able to move to allow expansion and contraction of the bridge so that the bridge would not be damaged.

3.

Explain the application of thermal effect for the following. (a) A bimetallic thermometer One end of the strip is fixed, the other end is attached with a pointer. The strip is made of iron and brass. These metals expand and contract at different rates which can show the rise or fall in temperatures. (b) Riveting Rivet is heated and fitted into the holes of the metal plates. The other end of the rivet is then flattened by hammering. When the rivet cools down, it holds the metal plates tightly.

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Secondary 1 Challenging Science Lesson 23: Worksheet Questions

4.

The diagram shows a bimetallic strip in an electric iron.

(a)

Explain why the bimetallic strip fails to maintain a constant temperature in an electric iron when electricity is switched on. Brass expands more so the strip will curl inwards and the contact point will not be broken at high temperatures.

(b)

What modification would you do in order to improve the electric iron set up? Switch the metals around. Brass nearer to contact point instead of iron.

5.

State and explain how the sensitivity of a thermometer would change, if any, when (a) the diameter of the capillary bore is decreased. Liquid in thermometer will show a larger rise for every one degree. (b) a thinner wall glass bulb is used. Heat energy can reach the liquid faster and the change in temperature can be observed quickly.

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Secondary 1 Challenging Science Lesson 23: Worksheet Questions

Homework Question 1. How does an ingestible thermometer help to prevent an athlete from getting a heat stroke? The pill which contains a quartz crystal sensor, is ingested by the athlete. The crystal vibrates at a frequency relative to the body's temperature, producing magnetic flux and transmitting a harmless, low-frequency signal through the body. This signal can then be retrieved by a recorder, outside of the body, that displays the core body temperature reading with an accuracy to within one-tenth of a degree, Celsius. When the core body temperature is close to 38° t he athlete is C, pulled immediately from the sport. Above 38° a person most likely will suffer a hea t stroke. C, Sometimes, the temperature monitoring unit is programmed with an alarm which sets off when an individual's core temperature reaches a certain level.

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