An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. It consists of a solenoid (wire) wrapped around a bar of iron or other ferromagnetic material. A solenoid is a coil of wire with electric current flowing through it. This gives the coil north and south magnetic poles and a magnetic field. The magnetic field of the solenoid magnetizes the iron bar and creates a more powerful magnet. Electromagnets are used as components of other electrical devices as well as in industry to lift or move heavy objects. Which of these would not increase the strength of an electromagnet?
A) adding more coils of wire
B) using a larger magnetic core
C) increasing the current flowing through it
D) increasing the distance between the wire and the core

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. It consists of a solenoid (wire) wrapped around a bar of iron or other ferromagnetic material. A solenoid is a coil of wire with electric current flowing through it. This gives the coil north and south magnetic poles and a magnetic field. The magnetic field of the solenoid magnetizes the iron bar and creates a more powerful magnet. Electromagnets are used as components of other electrical devices as well as in industry to lift or move heavy objects. Which of these would not increase the strength of an electromagnet?

A) adding more coils of wire

B) using a larger magnetic core

C) increasing the current flowing through it

D) increasing the distance between the wire and the core

It's too short. Write at least 20 characters to explain it well.

D

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.

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