Question

Orested is the unit of :

• A. Magnetic field
• B. Electrical current
• C. Electrical field
• D. Magnetic current

Hint:

Oersted (Oe) is a CGS unit for {magnetic field strength (\(H\))}. You might also encounter {gauss (G)}, another CGS unit for magnetic flux density (\(B\)). In the SI system, the corresponding units are:
Magnetic field strength (\(H\)): Ampere per meter (A/m)
Magnetic flux density (\(B\)): Tesla (T) Hans Christian Ørsted was a pioneer in electromagnetism, so his name is fittingly associated with a magnetic unit.

Answer 1

The Correct Option is A

Concept: Different physical quantities have specific units. The oersted (Oe) is a unit associated with magnetism. Step 1: Identifying the Oersted unit The oersted is a unit used in the CGS (centimeter-gram-second) system of units. It is named after Hans Christian Ørsted, who discovered the relationship between electricity and magnetism. Step 2: What quantity does the Oersted measure? The oersted is a unit of magnetic field strength, specifically the magnetizing field strength, often denoted by \(H\). In the CGS system, magnetic field strength \(H\) is measured in oersteds. The magnetic flux density \(B\) (another way to describe a magnetic field) is measured in gauss (G) in the CGS system. These are related by \(B = \mu H\), where \(\mu\) is the permeability of the medium. In vacuum, \(\mu = 1\) in the CGS EMU system, so \(B\) (in gauss) and \(H\) (in oersteds) are numerically equal in vacuum, though they represent distinct physical concepts. Step 3: SI unit for magnetic field strength In the SI system (International System of Units), the unit for magnetic field strength \(H\) is amperes per meter (A/m). The SI unit for magnetic flux density \(B\) is the tesla (T). \(1 \text{ Oe} = (1000 / 4\pi) \text{ A/m} \approx 79.577 \text{ A/m}\). \(1 \text{ G} = 10^{-4} \text{ T}\). Step 4: Analyzing the options
(1) Magnetic field: Correct. Oersted is a unit of magnetic field strength (\(H\)).
(2) Electrical current: The SI unit is ampere (A).
(3) Electrical field: The SI unit is volts per meter (V/m) or newtons per coulomb (N/C).
(4) Magnetic current: This is not a standard physical quantity in the same way as electric current. The concept of magnetic monopole current is theoretical. Therefore, oersted is a unit of magnetic field.