Questão 1
Questão
Ultrasound waves are partially ________ when they meet a boundary between two different media.
Questão 2
Questão
Ultrasound wave facts:
Responda
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Can be produced by electronic systems
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Have a frequency lower than 20000Hz
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Have a frequency higher than 20000Hz
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An electromagnetic wave beyond the red end of the visible spectrum
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An electromagnetic wave beyond the blue end of the visible spectrum
Questão 3
Questão
X-rays have a very short wave length and cause ionisation
Questão 4
Questão
X-rays can't be used to diagnose and treat medical conditions
Questão 5
Questão
Properties of X-rays:
Responda
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absorbed by metal and bone
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transmitted by soft tissue
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reflected by soft tissue
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doesn't effect photographic film in the same way as light
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effects photographic film in the same way as light
Questão 6
Questão
What is refraction?
Questão 7
Questão
A lens forms an image by refracting light
Questão 8
Questão
how is the nature of an image defined:
Questão 9
Questão
Which lens is used in a magnifying glass?
Questão 10
Questão
Visible light can be sent along optical fibres
Questão 11
Questão
What is long sight caused by?
Responda
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Eyeball being too short
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Eyeball being to long
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The lens is too weak
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The lens is too strong
Questão 12
Questão
Where can the eye focus on objects?
Responda
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Between the principal focus and the far point
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Between the near point and the far point
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Between the near point and the principal focus
Questão 13
Questão
The power of a lens is given by P=1/f
Questão 14
Questão
The greater the refractive index
Responda
-
The flatter the lens
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The thicker the lens
Questão 15
Questão
What does a camera lens and the eye have in common?
Responda
-
The CCDs in a digital camera is the equivalent of the retina
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They are both diverging lens'
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They are both converging lens'
Questão 16
Questão
Focal length is determined by:
Questão 17
Questão
Power is measured in Dioptres, D
Questão 18
Questão
The time period depends on the force being applied
Questão 19
Questão
The centre of mass of a symmetrical object is:
Questão 20
Questão
The centre of mass is that point where the mass of an object is thought to be
Responda
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Centered
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Concentrated
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Clear
Questão 21
Questão
What is the turning effect of a force called?
Questão 22
Questão
If the line of action of weight of an object lies inside the base of the object there will be a resultant moment and it will topple.
Questão 23
Questão
What is the moment of a force measured in?
Responda
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D (dioptres)
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m/s (metres per second)
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Nm (Newton-metres)
Questão 24
Questão
the centripetal force need to make an object perform circular motion increases as:
Responda
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Mass decreases
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Mass increases
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Radius decreases
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Radius increases
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Speed decreases
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Speed increases
Questão 25
Questão
The acceleration towards the centre of a circle changes the direction of the body and its speed.
Questão 26
Questão
What is the resultant force causing acceleration called?
Responda
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Centripecal force
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Centripical force
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Centripetal force
Questão 27
Questão
Liquids are compressible
Questão 28
Questão
Pressure in liquids is transmitted equally in all directions
Questão 29
Questão
Using different cross sectional areas of a hydraulic system means it can be used as a force multiplier.
Questão 30
Questão
what is produced around a wire when current flows though it?
Questão 31
Questão
The size of a force can be increased by:
Responda
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Increasing the size of the wire
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Increasing the size of the current
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Increasing the size of the voltage
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Increasing the strength of the magnetic field
Questão 32
Questão
When will the conductor not experience a force?
Questão 33
Questão
In flemings left hand rule:
Responda
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the first finger is the magnetic field direction
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The second finger is the strength of the current
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The second finger is the direction of the current
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The thumb is the direction of the current
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The thumb is the motion of the wire
Questão 34
Questão
Switch mode transformers use a lot of power when are switched on but no load is applied.
Questão 35
Questão
Switch mode transformers are much lighter and smaller than normal transformers working from a 50Hz mains supply
Questão 36
Questão
What does it mean if the electrical power input is equal to the electrical power output in a transformer?
Responda
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It is 100% efficient
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Heat energy was lost
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Its 0% efficient
Questão 37
Questão
In a step down transformer:
Responda
-
The potential difference across the secondary coil is more than the potential difference across the primary coil
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The potential difference across the secondary coil is less than the potential difference across the primary coil
Questão 38
Questão
In a step up transformer:
Responda
-
The potential difference across the secondary coil is less than the potential difference across the primary coil
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The potential difference across the secondary coil is more than the potential difference across the primary coil
Questão 39
Questão
What does an alternating current in the primary coil produce?
Questão 40
Questão
What does a changing magnetic field induce in a transformer?
Questão 41
Questão
If a magnet is moved into a coil or wire of potential difference is induced across the ends of the coil
Questão 42
Questão
If an electrical conductor cuts through a magnetic field a potential difference is induced across the ends of the conductor
Questão 43
Questão
Which of these options are part of the basic structure of a transformer?
Responda
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Two coils around a soft core
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One coil around a soft core
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De magnetising soft iron
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Magnetising soft iron
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Layers of iron (Laminated)
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One layer (meaning laminated)