Question

Assertion:
MRI is used to scan the inner organs of the human body by penetrating very intense magnetic fields.
Reason:
By use of a very intense magnetic field, very high-resolution images can be obtained.
a) both assertion and reason are correct and reason is the correct explanation.
b) both are correct but reason is not correct explanation
c) assertion is correct, bit reason is incorrect.
d) assertion is correct and reason supports assertion.

Answer 1

Very high magnetic fields and radio waves are used to produce detailed images of the human body which can’t be collected using normal methods. The protons present inside our body are magnetic in nature and thus they react to even small changes in magnetic fields.

Complete answer:
Magnetic resonance imaging (MRI) is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body. Most of the human body is made up of water molecules, which consist of hydrogen and oxygen atoms. At the centre of each hydrogen atom is an even smaller particle called a proton. Protons are like tiny magnets and are very sensitive to magnetic fields. When you lie under the powerful scanner magnets, the protons in your body line up in the same direction, in the same way, that a magnet can pull the needle of a compass. Short bursts of radio waves are then sent to certain areas of the body, knocking the protons out of alignment. When the radio waves are turned off, the protons realign. This sends out radio signals, which are picked up by receivers. These signals provide information about the exact location of the protons in the body. They also help to distinguish between the various types of tissue in the body, because the protons in different types of tissue realign at different speeds and produce distinct signals. In the same way that millions of pixels on a computer screen can create complex pictures, the signals from the millions of protons in the body are combined to create a detailed image of the inside of the body.

So, the correct answer is “Option A”.

Note:
MRI cannot always distinguish between malignant tumours or benign disease (such as breast fibroadenomas), which could lead to false positive results. MRI is not painful, but the patient must remain still in an enclosed machine, which may be a problem for claustrophobic patients.