The (NPN) transistor in this circuit is used to <em>switch a current</em>. When it switches current ON ... acting like a closed switch ... the light goes on.
It's kind of mystifying WHY all of this technological complexity is necessary. There's already a switch in the circuit ... (the two little circles above the 1K resistor in the base circuit with the tilted line between them). That switch could just as well be used, in place of the transistor, to directly switch the current through the light. Why use one switch to control a transistor to make it behave like another switch ? ?
The only actual necessity for doing this that makes sense is if the switch in the base circuit is a tiny low-power switch, and the transistor is a big moose high-power transistor, controlling a high-current, multi-kilowatt searchlight.
A place you might actually find an application like this would be in your car. A small current through the ignition switch behind the key is used to turn on a high-power transistor under the hood, which controls the huge current to the starter motor. That way, they avoid running a 100-Ampere cable in and out of the ignition switch, and needing a several-hundred-Ampere switch in the steering column behind the key.
many answers to this question so chose whatever you link:
- urbanisation -> more people, humanity keeps on living, more job opportunities etc
- source of income for farmers
- source for food (farming)
- source for trees (eg, to create wood (houses), or to use logs for fire)
Answer:
A. 2HCl + Mg(OH)2 + 2H2O + MgCl2
hope it helps
Answer:
E=1.50\times 10^{-18}J
Explanation:
Energy of the one dimensional infinite well,
Given that, 
For the ground state n=1,
Therefore energy is,
Answer:
24.9 m
Explanation:
A triangle is a polygon with three sides and three angles. There are different types of triangles such as the equilateral triangle, isosceles triangle, scalene triangle, right angled triangle.
You walk 21.5 m straight east and then 12.5 m straight north. This forms a right angled triangle with a horizontal distance of 21.5 m, a vertical distance of 12.5 m and the hypotenuse is the distance between the ending and starting point. Let x represent the distance between the ending and starting point. Therefore using Pythagoras theorem:
x² = 21.5² + 12.5²
x² = 462.25 + 156.25
x² = 618.5
Taking square root of both sides:
√x² = √618.5
x = √618.5
x = 24.9 m = distance between the ending and starting point.
