Heat and Temperature (And 6th year Magnetism):

Question 1

temperature

Answer 1

the measure of the hotness or coldness of a body

Question 2

SI unit for temperature

Answer 2

the kelvin K

Question 3

for practical work

Answer 3

ºC

Question 4

ºC =

Answer 4

K - 273.15

Question 5

Δθ = 5ºC =

Answer 5

5K

Question 6

thermometric property

Answer 6

the physical property of a thermometer that changes measurable with temperature

Question 7

4 thermometric properties

Answer 7

length of a column of mercury
emf of a thermocouple
resistance of a wire
colour of liquid crystals

Question 8

what is the standard thermometer

Answer 8

the laboratory mercury thermometer

Question 9

to calibrate a liquid in glass thermometer experiment

calibration graph, y axis

Answer 9

length cm

Question 10

to calibrate a thermometer experiment

calibration graph, x axis

Answer 10

temperature ºC

Question 11

to calibrate a liquid in glass thermometer

2 points on accuracy

Answer 11

1. use a stirrer to ensure water has uniform temperature

2. avoid error of parallax when using the half metre stick to measure the length of the liquid in a glass tube

Question 12

calibrating a thermocouple thermometer y-axis

Answer 12

emf (mV)

Question 13

what do you place in the substance you want to check temperature of with thermocouple thermometer

Answer 13

hot junction

Question 14

reference junction

Answer 14

cold junction

Question 15

how to find temperature of reference junction

Answer 15

finding the value of the point of intersection of the graph and the x-axis

Question 16

2 different thermometers

Answer 16

don’t agree

Question 17

the values of different thermometers

Answer 17

will most likely not be the same

Question 18

why do the 2 values not agree?

Answer 18

different thermometers based on different thermometric properties respond in a different way to a given rise in temperature giving somewhat different values

Question 19

is there a correct thermometer?

Answer 19

we choose a standard thermometer against which all other thermometers can be compared

Question 20

what is special about a clinical thermometer?

Answer 20

there is a constriction

Question 21

what is the constriction in the medical thermometer designed to do?

Answer 21

designed to stop the liquid from falling back into the reservoir when the thermometer is taken out of the patient’s mouth

Question 22

how is the liquid in the medical thermometer got back into the reservoir

Answer 22

it is shaken before used on next patient

Question 23

2 uses of a thermocouple thermometer

Answer 23

in an oven or a boiler

Question 24

how is the thermocouple thermometer read?

Answer 24

the emf generated would be translated to a temperature reading

Question 25

what flows between hotter and cooler substance?

Answer 25

heat energy

Question 26

atoms in hot and cold substances moving in

Answer 26

moving in a 3 dimensional type of vibration

Question 27

atoms in hot and cold substances have what energy

Answer 27

kinetic and potential energy

Question 28

energy inside hot and cold substances

Answer 28

internal energy

Question 29

which substance has more internal energy

Answer 29

the hotter substance

Question 30

why does the hotter substance have more internal energy?

Answer 30

the kinetic energy is greater due to vibrations in the hotter substance

Question 31

what is heat?

Answer 31

the form of energy transferred from the hotter substance to the cooler substance as a result of the temperature difference between them

Question 32

definition of heat capacity

Answer 32

the heat energy needed to change the temperature of an object by 1K

Question 33

symbol of heat capacity

Answer 33

C

Question 34

unit of heat capacity

Answer 34

JK -1

Question 35

definition of specific heat capacity

Answer 35

the heat energy needed to change the temperature of 1 Kg of the object by 1 K

Question 36

symbol of specific heat capacity

Answer 36

c

Question 37

unit of specific heat capacity

Answer 37

J Kg -1 K-1

Question 38

energy needed to change temperature formula

Answer 38

mcΔθ

Question 39

m

Answer 39

mass of substance

Question 40

c

Answer 40

specific heat capacity

Question 41

Δθ

Answer 41

temperature change

Question 42

energy needed to change temperature =

Answer 42

kinetic energy (1/2 m v squared )

Question 43

to measure specific heat capacity by an electrical method. what do you do before the experiment?

Answer 43

let the arrangement stand for several minutes before the electricity is switched on

Question 44

to measure specific heat capacity by an electrical method. why do you let it stand for a few minutes

Answer 44

to ensure that t he temperature of the liquid equals the temperature of the calorimeter

Question 45

to measure specific heat capacity by an electrical method. 4 steps in the experiment

Answer 45

1. record the mass of the calorimeter and mass of the liquid 2. record the initial temperature of the liquid and calorimeter 3. allow current to flow for 5 minutes, record electrical energy supplied by using the joulemeter 4. record the final temperature of the liquid and calorimeter

Question 46

to measure specific heat capacity by an electrical method. electrical energy supplied =

Answer 46

heat energy gain + heat energy gain of calorimeter

Question 47

to measure specific heat capacity by an electrical method. 2 points on accuracy

Answer 47

- avoid small rise in temperature as measuring small values results in greater percentage errors - use a sensitive thermometer to get a precise value of the temperature rise

Question 48

what do storage heaters contain?

Answer 48

concrete blocks with a large value of specific heat capacity

Question 49

when do storage heaters heat up and why?

Answer 49

heat up at night when the demand for electricity is less and is cheaper

Question 50

why do storage heaters absorb large amounts of heat?

Answer 50

because of the large heat capacity

Question 51

what do storage heaters do during the day?

Answer 51

they cool down by releasing their heat to the surrounding air

Question 52

water can

Answer 52

absorb large amounts of heat

Question 53

very useful liquid in radiators

Answer 53

water

Question 54

to measure specific heat capacity by a mechanical method what do you do before the experiment

Answer 54

let sit for several minutes before copper is added

Question 55

to measure specific heat capacity by a mechanical method what do you do before the experiment, why do you let sit for several minutes before copper is added?

Answer 55

ensures that the temperature of the liquid equals the temperature of the calorimeter

Question 56

heat loss of hot copper =

Answer 56

heat energy gain of liquid + heat energy gain of calorimeter

Question 57

what is the calorimeter usually made of?

Answer 57

copper

Question 58

water at 100º and water at 20º added, heat change of hotter one

Answer 58

100º - x

Question 59

water at 100º and water at 20º added, heat change of cooler one

Answer 59

x-20º

Question 60

when calculating the moment of a force causing something to move in a circle, what is the perpendicular distance?

Answer 60

the radius

Question 61

moment of a force causing something to move in a circle

Answer 61

IlB x radius

Question 62

moment of a couple causing something to move in a circle

Answer 62

IlB x diameter

Question 63

magnetic flux formula

Answer 63

Φ = BA

Question 64

Φ

Answer 64

magnetic flux

Question 65

B

Answer 65

magnetic flux density

Question 66

A

Answer 66

area through which magnetic flux density is acting

Question 67

unit of magnetic flux

Answer 67

tesla x m2

Question 68

Faraday's law - ENGLISH

Answer 68

if the magnetic flux lines passing through a circuit change, then an emf is induced the induced emf is proportional to the rate of change of magnetic flux passing through the circuit

Question 69

Faraday's law - MATHS

Answer 69

emf ∝ dΦ/dt emf = -N dΦ/dt (N= number of turns in coil) (ignore negative in maths equation)

Question 70

Lenz's law - ENGLISH

Answer 70

The induced emf makes a current flow in such a direction as to oppose the change that caused it

Question 71

ac Resultant voltage =

Answer 71

source voltage - induced voltage

Question 72

ac if the frequency of the a.c source is increased

Answer 72

the induced voltage is greater and the resultant voltage is smaller, bulb is less bright

Question 73

ac if an iron core is inserted into a solenoid

Answer 73

magnetic flux is stronger, greater induced voltage, decrease in resultant voltage, less bright bulb

Question 74

dc initially

Answer 74

current flows in the same direction, magnetic field is constant, no emf???

Question 75

dc maximum brightness

Answer 75

takes time for maximum brightness to be reached

Question 76

dc increase briefly induced emf 2

Answer 76

more turns of a wire of the solenoid | insert an iron core into the solenoid

Question 77

dc if the switch is opened

Answer 77

self induction happens for a brief time interval, small delay in the bulb's brightness reducing to zero