Across a metallic conductor of non-uniform cross section a constant potential difference is applied. The quantity which remains constant along the conductor is:
Show Hint
The potential difference across the metallic conductor is non-uniform in nature. The cross-section of the metallic conductor is also non-uniform.
- drift velocity
- electric field
- current density
- current
The Correct Option is D
Approach Solution - 1
The correct option is(D): current.
As all the cross sections of the conductor are considered to be in series, the current should be constant.
We will identify the quantity unaffected by the non-uniformity of the metallic conductor.
- The potential difference across the metallic conductor is non-uniform in nature.
- The cross-section of the metallic conductor is also non-uniform.
Current is the amount of charge passing through a point in a given time. The rate of flow of charge is also termed as current. It is measured in amperes. It does not depend on any physical characteristics of the medium. If a medium is conducting in nature, then a charge will flow through it.
Drift velocity is the average velocity acquired by charged particles like electrons, in a material as a result of an electric field. Applying an electric field applies a net flow in a direction, known as the drift.
Electric field is electric force per unit charge. It depends upon the separation of the test charge and the electric field and the charge produced by the electric field.
Current density refers to the amount of charge passing through a unit area in a unit of time. However, if the material is non-uniform, then the current density will also be non-uniform.
Hence, from the above explanation, it is clear that current is not affected when a constant potential difference is applied across a non-uniform metallic conductor.
Thus, the correct option is D) current.
Note: Current just depends on the potential difference applied across a conductor. However, the flow of current is affected by the resistance in it. The higher the resistance, the lesser the current flow, or vice-versa.
Approach Solution -2
The correct option is D: Current
Explanation:
Current is the charge flown per unit of time. It should remain the same along any cross section as no accumulation of charge is there in the conductor. Therefore, current remains constant.
- The resistance is given by R = ρL/A, where ρ is resistivity (constant for a given material). When the area of the cross-section of the resistor varies, the resistance also varies.
- According to Ohm's law, V=IR. As I is constant and R varies, the potential difference varies along the cross-section and hence the electric field also changes in the cross-section.
- Drift velocity can be found by vd=I/neA which also changes as I stay constant and A varies.
- Current density is given as J=I/A. As A varies and I stay constant, the current density also changes.
Hence, the correct answer is option D) Across a metallic conductor of non-uniform cross-section a constant potential difference is applied. The quantity which remains constant along the conductor is current
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Concepts Used:
Classification of Animals
Classification of Animal Kingdom:
One of the most fundamental forms of classification of animals is the presence or absence of the notochord. Hence, two major groups exist, namely: Chordates and Non-chordates
Non-chordates and the Chordates-
- The notochord is a flexible rod made out of a material similar to cartilage. If an animal has a notochord during any stage of its life, it is classified as a chordate. Contrary to popular belief, chordates do not exclusively include vertebrates.
- There are invertebrates that possess a notochord during some point in their lives and hence, are classified as chordates. Thus all vertebrates are chordates but not all chordates are vertebrates.
Non-chordates-
- Non-chordates are animals without a notochord – the rod-like elastic structure that supports the body. This phylum consists of a small group of worm-like, marine species with an organ-system level of organization.
- Members of phylum Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata and Hemichordata fall under Non-chordates
Vertebrates Classification:
The subphylum Vertebrata is divided into five classes of vertebrates. These five classes of vertebrates comprise of all the species of animals and have developed vertebral column as well as an internal skeleton.
Other characteristic features of vertebrates are-
- Presence of a true vertebral column and internal skeleton with muscle attachment points for body movement.
- A front-side muscular heart with two, three or four chambers.
- Kidneys for excretion and osmoregulation
- A paired appendages which may be fins or limbs.
- Possess notochord during the embryonic stage.
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