Hussain Basheer
Quiz por , criado more than 1 year ago

Medical Physics Quiz sobre Generators of high frequency electromagnetic waves. Frequency ranges used in physiotherapy. Inductive and capacitive methods. Determination of the power of electromagnetic wave sources. Safety technique - Medical Physics -MCQs, criado por Hussain Basheer em 23-11-2018.

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Hussain Basheer
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Generators of high frequency electromagnetic waves. Frequency ranges used in physiotherapy. Inductive and capacitive methods. Determination of the power of electromagnetic wave sources. Safety technique - Medical Physics -MCQs

Questão 1 de 20

1

Which of the following human organs and tissues have the least thermal conductivity?

Selecione uma das seguintes:

  • Muscles

  • Brain

  • Skin and fat

Explicação

Questão 2 de 20

1

Which of the following diagnostic/therapeutic methods cause deep tissue heating?

Selecione uma das seguintes:

  • Thermography

  • High frequency electric current therapy

  • Deep x-ray therapy

Explicação

Questão 3 de 20

1

Faradization is a method for:

Selecione uma das seguintes:

  • Electro-stimulation with low frequency pulsed current

  • High frequency electromagnetic therapy

  • Interferential current therapy of deep-seated tissue

Explicação

Questão 4 de 20

1

The most common frequency used in high-frequency electro-stimulation is:

Selecione uma das seguintes:

  • 20 Hz

  • 20 kHz

  • 2 MHz

Explicação

Questão 5 de 20

1

Modern electromyography methods rely on the following parameter (chose one):

Selecione uma das seguintes:

  • Rheobase

  • Chronaxie

  • Accommodation coefficient

Explicação

Questão 6 de 20

1

Thermography is a medical imaging method that:

Selecione uma das seguintes:

  • Is harmless

  • Has high resolution

  • With diagnostic significance similar to MRI

Explicação

Questão 7 de 20

1

Which of the following body fluids and tissues has the least electrical conductivity?

Selecione uma das seguintes:

  • Blood

  • Bones

  • Bone marrow

Explicação

Questão 8 de 20

1

Electric resistance (R) is inversely proportional to:

Selecione uma das seguintes:

  • Electric conductance (G)

  • Frequency (f)

  • Period (T)

Explicação

Questão 9 de 20

1

What is the main effect that causes heating in microwave diathermy, and also in the microwave oven (f = 2.45 GHz)?

Selecione uma das seguintes:

  • Resonance: water molecules oscillate with the same frequency

  • Dielectric heating: electric dipoles of water are made to rotate

  • Refraction: bending of waves inside the substance

Explicação

Questão 10 de 20

1

Electric potential difference is measured in units of volts (V) that represent the ratio of:

Selecione uma das seguintes:

  • Charge per time, Q/t

  • Energy per charge, E/Q

  • Energy per distance, E/x

Explicação

Questão 11 de 20

1

Which of following electric currents is the most dangerous for the human body?

Selecione uma das seguintes:

  • High frequency AC

  • Low frequency AC

  • Pulsed current

Explicação

Questão 12 de 20

1

Which of the following currents will cause stimulation in excitable tissue (nerves or muscles)?

Selecione uma das seguintes:

  • Low frequency, pulsed, above threshold

  • Low frequency, alternating, below threshold

  • High frequency, alternating, above threshold

Explicação

Questão 13 de 20

1

High-frequency generators produce electromagnetic waves with:

Selecione uma das seguintes:

  • Aperiodic behavior

  • Constant amplitude

  • Gradually damping amplitude

Explicação

Questão 14 de 20

1

Which of the following currents causes differential heating in tissues?

Selecione uma das seguintes:

  • Pulsed current

  • High frequency current

  • DC current

Explicação

Questão 15 de 20

1

Which of the following features are common forelectrosurgery and electrostimulation?

Selecione uma das seguintes:

  • The frequency

  • The shape of the electrodes

  • The use of alternating current

Explicação

Questão 16 de 20

1

Specific heat capacity is defined as:

Selecione uma das seguintes:

  • The amount of heat needed to raise the temperature of 1 kg of substance by 1 degree Kelvin (or Celsius)

  • The heat released during the controlled burn of 1 kg of substance

  • The heat gain in a substance when Gibbs free energy increases by 1 joule

Explicação

Questão 17 de 20

1

Electrosurgical procedures apply alternating current in the radio frequency (RF) range (100 kHz - 5 MHz) directly to the tissue. Why during electrosurgery there is no nerve and muscular stimulations?

Selecione uma das seguintes:

  • High frequencies currents do not penetrate deep enough

  • Oscillations are much faster than membrane depolarization time

  • The power is below stimulation threshold

Explicação

Questão 18 de 20

1

What is the heating mechanism of high frequency alternating current (2MHz)?

Selecione uma das seguintes:

  • Brief polarization of tissue

  • Oscillations of ionized molecules, rotation of dipoles and associated collisions

  • Absorption of energy from the electromagnetic waves

Explicação

Questão 19 de 20

1

When an inductor (L) and a capacitor (C) are connected in series, the resulting (L-C) electric circuit is called:

Selecione uma das seguintes:

  • Operational amplifier (compares and amplifies signal)

  • Current rectifier (converts AC into DC)

  • Harmonic oscillator (used to emit radio waves)

Explicação

Questão 20 de 20

1

The Earth surface is (reasonably) constant potential reference, and for that reason taken to be the :

Selecione uma das seguintes:

  • Infinite potential

  • Negative potential

  • Zero potential

Explicação

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