Answer:
<em>a. True</em>
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Explanation:
I'll assume the question is about magnetic latches and locks.
Magnetic door locks use an electromagnetic force to stop doors from opening, so they are ideal for security. There are two main types of electric locking devices. Locking devices can either be a fail-secure locking device that remains locked when power is lost, or a fail-safe locking device that is unlocked when de-energized. An electromagnetic lock creates a magnetic field when energized or powered up, this causes an electromagnet and armature plate to become attracted to each other strongly enough to keep a door from opening.
Answer:
See explanation
Explanation:
1) There are two main types of waves;
Mechanical waves and electromagnetic waves.
Mechanical waves usually require a medium for propagation, e.g sound, waves on a spiral spring, etc
Electromagnetic waves do not require a medium for propagation e.g microwaves, x-rays etc
2) The phenomenon is known as refraction. Refraction occurs at the boundary between two media because of the change in the speed of a wave as it moves from one medium to another.
