Answer:
The heating element of the heater is made up of alloy which has very high resistance so when current flows through the heating element, it becomes too hot and glows red. But the resistance of cord which is usually of copper or aluminum is very low so it does not glow.
From the diagram we have that



Therefore the direction is 30° from east of south
Answer:
Explanation:
Energy of electron in n = 4 state
= - 13.6/4² =- 0.85 eV
So energy needed to extract it from atom = .85 eV.
A gravitational field is the field generated by a massive body, that extends into the entire space. Every object with mass m experiences a force F when immersed in a gravitational field. The intensity of the force is equal to

where

is the gravitational constant, M is the mass of the source of the field (e.g. the mass of a planet), and r is the distance between the object and the source of the field. The force is always attractive.
A possible way to measure the intensity of a gravitational field is by measuring the acceleration a of the object immersed in this field. In fact, for Newton's second law we have:

but since

we can write

Therefore, by measuring the acceleration of the object, we also measure the intensity of the field.