An earth rod can be repersented approximately by a copper hemisphere buried in the ground, with its flat surface level with the surface of the ground. If / is the current flowing into the ground, and p is the resistivity of the soil, show that the magnitude of the electric field strength at a distance r from the centre is as follows: (5 Marks)

r: A=2Πr^2 J=I/A=I/2Πr^2, E=pI/2Πr^2

An electromagnet with two poles, each measuring 25 x 25 mm, is required to attract a steel armature with a force of 200 N. If there are equal airgaps between the poles and the armature, determine the required magnetic flux density in the airgaps?. (5 Marks)

Answer: see how this came to be

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1An earth rod can be repersented approximately by a copper hemisphere buried in the ground, with its flat surface level with the surface of the ground. If / is the current flowing into the ground, and p is the resistivity of the soil, show that the magnitude of the electric field strength at a distance r from the centre is as follows:
(5 Marks)
1. AA = 2Πr^2
2. Br: A=2Πr^2 J=I/A=I/2Πr^2, E=pI/2Πr^2
2An electromagnet with two poles, each measuring 25 x 25 mm, is required to attract a steel armature with a force of 200 N. If there are equal airgaps between the poles and the armature, determine the required magnetic flux density in the airgaps?.
(5 Marks)
1. AAnswer: see how this came to be

Description: Bachelors Degree University Level Quiz on Electromechanics past paper quiz, created by Study Corner on 16/05/2016.
Author: Study Corner
Language: English
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