2357393
Descripción
Test por Gabi Germain, actualizado hace más de 1 año
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Creado por Gabi Germain
hace casi 10 años
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Pregunta 1
Pregunta
Ultrasound waves are partially ________ when they meet a boundary between two different media.
Respuesta
-
Refracted
-
Reflected
Pregunta 2
Pregunta
Ultrasound wave facts:
Respuesta
-
Can be produced by electronic systems
-
Have a frequency lower than 20000Hz
-
Have a frequency higher than 20000Hz
-
An electromagnetic wave beyond the red end of the visible spectrum
-
An electromagnetic wave beyond the blue end of the visible spectrum
Pregunta 3
Pregunta
X-rays have a very short wave length and cause ionisation
Respuesta
- True
- False
Pregunta 4
Pregunta
X-rays can't be used to diagnose and treat medical conditions
Respuesta
- True
- False
Pregunta 5
Pregunta
Properties of X-rays:
Respuesta
-
absorbed by metal and bone
-
transmitted by soft tissue
-
reflected by soft tissue
-
doesn't effect photographic film in the same way as light
-
effects photographic film in the same way as light
Pregunta 6
Pregunta
What is refraction?
Respuesta
-
change of direction of light as it passes from one medium to another
-
change of direction of sound waves as they pass from one medium to another
Pregunta 7
Pregunta
A lens forms an image by refracting light
Respuesta
- True
- False
Pregunta 8
Pregunta
how is the nature of an image defined:
Respuesta
-
Size relative to the object
-
If the light rays cross
-
Real or virtual
-
Upright or inverted
-
Distance from focal length
Pregunta 9
Pregunta
Which lens is used in a magnifying glass?
Respuesta
-
Converging
-
Diverging
Pregunta 10
Pregunta
Visible light can be sent along optical fibres
Respuesta
- True
- False
Pregunta 11
Pregunta
What is long sight caused by?
Respuesta
-
Eyeball being too short
-
Eyeball being to long
-
The lens is too weak
-
The lens is too strong
Pregunta 12
Pregunta
Where can the eye focus on objects?
Respuesta
-
Between the principal focus and the far point
-
Between the near point and the far point
-
Between the near point and the principal focus
Pregunta 13
Pregunta
The power of a lens is given by P=1/f
Respuesta
- True
- False
Pregunta 14
Pregunta
The greater the refractive index
Respuesta
-
The flatter the lens
-
The thicker the lens
Pregunta 15
Pregunta
What does a camera lens and the eye have in common?
Respuesta
-
The CCDs in a digital camera is the equivalent of the retina
-
They are both diverging lens'
-
They are both converging lens'
Pregunta 16
Pregunta
Focal length is determined by:
Respuesta
-
Refractive index of the material
-
Thickness of the lens
-
Curvature of the lens
-
Light rays
Pregunta 17
Pregunta
Power is measured in Dioptres, D
Respuesta
- True
- False
Pregunta 18
Pregunta
The time period depends on the force being applied
Respuesta
- True
- False
Pregunta 19
Pregunta
The centre of mass of a symmetrical object is:
Respuesta
-
In the middle
-
Along its axis of symmetry
Pregunta 20
Pregunta
The centre of mass is that point where the mass of an object is thought to be
Respuesta
-
Centered
-
Concentrated
-
Clear
Pregunta 21
Pregunta
What is the turning effect of a force called?
Respuesta
-
Moment
-
Resultant
Pregunta 22
Pregunta
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.
Respuesta
- True
- False
Pregunta 23
Pregunta
What is the moment of a force measured in?
Respuesta
-
D (dioptres)
-
m/s (metres per second)
-
Nm (Newton-metres)
Pregunta 24
Pregunta
the centripetal force need to make an object perform circular motion increases as:
Respuesta
-
Mass decreases
-
Mass increases
-
Radius decreases
-
Radius increases
-
Speed decreases
-
Speed increases
Pregunta 25
Pregunta
The acceleration towards the centre of a circle changes the direction of the body and its speed.
Respuesta
- True
- False
Pregunta 26
Pregunta
What is the resultant force causing acceleration called?
Respuesta
-
Centripecal force
-
Centripical force
-
Centripetal force
Pregunta 27
Pregunta
Liquids are compressible
Respuesta
- True
- False
Pregunta 28
Pregunta
Pressure in liquids is transmitted equally in all directions
Respuesta
- True
- False
Pregunta 29
Pregunta
Using different cross sectional areas of a hydraulic system means it can be used as a force multiplier.
Respuesta
- True
- False
Pregunta 30
Pregunta
what is produced around a wire when current flows though it?
Respuesta
-
Heat
-
Magnetic field
Pregunta 31
Pregunta
The size of a force can be increased by:
Respuesta
-
Increasing the size of the wire
-
Increasing the size of the current
-
Increasing the size of the voltage
-
Increasing the strength of the magnetic field
Pregunta 32
Pregunta
When will the conductor not experience a force?
Respuesta
-
When parallel to the magnetic field
-
When bearer to the magnetic field
Pregunta 33
Pregunta
In flemings left hand rule:
Respuesta
-
the first finger is the magnetic field direction
-
The second finger is the strength of the current
-
The second finger is the direction of the current
-
The thumb is the direction of the current
-
The thumb is the motion of the wire
Pregunta 34
Pregunta
Switch mode transformers use a lot of power when are switched on but no load is applied.
Respuesta
- True
- False
Pregunta 35
Pregunta
Switch mode transformers are much lighter and smaller than normal transformers working from a 50Hz mains supply
Respuesta
- True
- False
Pregunta 36
Pregunta
What does it mean if the electrical power input is equal to the electrical power output in a transformer?
Respuesta
-
It is 100% efficient
-
Heat energy was lost
-
Its 0% efficient
Pregunta 37
Pregunta
In a step down transformer:
Respuesta
-
The potential difference across the secondary coil is more than the potential difference across the primary coil
-
The potential difference across the secondary coil is less than the potential difference across the primary coil
Pregunta 38
Pregunta
In a step up transformer:
Respuesta
-
The potential difference across the secondary coil is less than the potential difference across the primary coil
-
The potential difference across the secondary coil is more than the potential difference across the primary coil
Pregunta 39
Pregunta
What does an alternating current in the primary coil produce?
Respuesta
-
A changing magnetic field
-
A constant current
Pregunta 40
Pregunta
What does a changing magnetic field induce in a transformer?
Respuesta
-
An alternating potential difference across the secondary coil
-
An constant potential difference across the secondary coil
Pregunta 41
Pregunta
If a magnet is moved into a coil or wire of potential difference is induced across the ends of the coil
Respuesta
- True
- False
Pregunta 42
Pregunta
If an electrical conductor cuts through a magnetic field a potential difference is induced across the ends of the conductor
Respuesta
- True
- False
Pregunta 43
Pregunta
Which of these options are part of the basic structure of a transformer?
Respuesta
-
Two coils around a soft core
-
One coil around a soft core
-
De magnetising soft iron
-
Magnetising soft iron
-
Layers of iron (Laminated)
-
One layer (meaning laminated)
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