Explain why there is total internal reflection in an optical fibres

The respiratory system removes oxygen and water from the body. select the best answer from the choices provided t f

In the circuit shown below, with each bulb holding a resistance of 60 ohms, how many amps of current are flowing? express your number as a decimal.

Tall pacific coast redwood trees can reach heights of about 100 m. if air drag is negligibly small, how fast is a sequola cone moving when it reaches the ground f it dropped from the top of a 100 m tree?