Answer:
They have a dual wave-particle nature.
Explanation:
Electromagnetic waves consist of periodic oscillations of electric and magnetic field in a plane perpendicular to the direction of motion of the wave (in fact, they are also classified as transverse waves).
Electromagnetic waves have a wave nature, however they also have particle nature - in fact, it has been proved in some experiment (e.g. photoelectric effect) that in some conditions they act as packets of particles - called photons. Therefore, the option
They have a dual wave-particle nature.
is correct.
Other options are wrong because:
They are all invisible. --> False because visible light (which is part of the electromagnetic spectrum, so they are electromagnetic waves) is visible
They can only travel without a medium. --> False because they can also travel in a vacuum
They are slower than sound waves. --> False because they travel much faster (they travel at the speed of light in a vacuum,
, while sound travels at 343 m/s in air, for instance)
Answer:
True
Explanation:
When an object is held higher, it has more potential energy because more energy is stored from its higher position to swing further than it would have, had it been held lower.
To solve this problem we will use a free body diagram that allows us to determine the Normal Force.
In general, the normal force would be equivalent to

Since the skier is standing on two skis, his weight will be divide by two

Pressure is given as the force applied in a given area, that is

Replacing F with N'


Our values are given as,




Replacing we have that


Therefore the pressure exerted by each ski on the snow is 776.01Pa
Answer:
the radii of curvature is 30 cm.
Explanation:
given,
object is place at = 45 cm
image appears at = 90 cm
focal length = ?
refractive index = 1.5
radii of curvature = ?


f = 30 cm
using lens formula





R = 30 cm
hence, the radii of curvature is 30 cm.