Cada pregunta de este test está cronometrada.
True or false? When X-rays are being taken, barium meals are used to provide a contrast medium to show soft tissues.
What does a charge-coupled device (CCD) do in X-ray imaging?
Create an electrical charge to start emission of X-rays
Convert X-rays to light to show an image
Create a computerised tomography, 3D, scan
What is the frequency of ultrasound waves?
Less than 20Hz
Between 20Hz and 20,000Hz
Greater than 20,000Hz
True or false? If an ultrasound transducer is used to measure the length of an eyeball, this is called an I-scan.
Which of these formulae is used to calculate the depth of a boundary using ultrasound?
depth = speed of wave * transit time
depth = 2 * speed of wave * transit time
depth = 0.5 * speed of wave * transit time
True or false? Snell's law states that the sine of the incident angle divided by the sine of the refractive angle is the same for each type of substance (e.g. it is the same in all glass).
Which way would the light ray refract if it entered a medium with a higher refractive index?
Away from the normal
Towards the normal
It would not refract
When will total internal reflection occur?
When the angle of incidence is less than the critical angle
When the angle of incidence is equal to the critical angle
When the angle of incidence is greater than the critical angle
True or false? The equation connecting refractive index and critical angle is n = sin c.
True or false? The principal focus of a converging lens is the point from which light rays spread out.
True or false? The formula to calculate magnification is image height/object height.
Which of these statements are true about the image formed by a converging lens where the object is beyond the principal focus?
Virtual
Real
Diminished
Magnified
Upright
Inverted
Which of these statements are true about the image formed by a converging lens where the object is between the lens and the principal focus?
Which of these statements are true about the image formed by a diverging lens?
Which part of the eye is light focused on?
Cornea
Iris
Retina
Lens
Ciliary muscles
Sclera
Suspensory ligaments
Pupil
Which part of the eye adjusts the thickness of the eye lens?
True or false? The range of vision is the distance between the near point and the far point; for the human eye, this is between 25cm and infinity.
What is the unit of power of a lens?
Watt
Dioptre
Farad
Which of these statements are true about myopia (short sight)?
The eyeball is too short
The eyeball is too long
The lens is too powerful
The lens is too weak
The image forms in front of the retina
The image forms behind the retina
A converging lens can correct it
A diverging lens can correct it
Which of these statements are true about hyperopia (long sight)?