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Questions and Answers

Who discovered radio waves?

  • James Clerk Maxwell
  • Heinrich Hertz (correct)
  • William Herschel
  • Hans Christian Oersted

What happens to wavelength as frequency increases?

  • Wavelength increases
  • Wavelength is inversely proportional (correct)
  • Wavelength remains constant
  • Wavelength decreases

What is the primary application of infrared waves?

  • Medical imaging (correct)
  • WiFi communications
  • Traffic light signaling
  • Radio broadcasting

Which electromagnetic wave is visible to the naked eye?

<p>Visible light (C)</p> Signup and view all the answers

What is the role of UVA radiation?

<p>Used to treat skin conditions (B)</p> Signup and view all the answers

Which electromagnetic wave has the shortest wavelength?

<p>Gamma rays (A)</p> Signup and view all the answers

What is a significant application of radar technology?

<p>Radio detection and ranging (B)</p> Signup and view all the answers

What causes the deflection of a compass needle according to Oersted's discovery?

<p>Current carrying wire (A)</p> Signup and view all the answers

Which of the following best describes the application of X-rays?

<p>Dental imaging (A)</p> Signup and view all the answers

What significant discovery is associated with gamma rays?

<p>Paul Villard (B)</p> Signup and view all the answers

Which of the following statements about the effects of ultraviolet light is correct?

<p>Overexposure may lead to skin cancer. (A)</p> Signup and view all the answers

What is one of the key effects of infrared radiation?

<p>May lead to eye damage with prolonged exposure. (C)</p> Signup and view all the answers

Which consequence is associated with exposure to X-rays?

<p>It can cause skin burns. (A)</p> Signup and view all the answers

What is the primary function of a concave mirror used by dentists?

<p>To create magnified images of teeth (D)</p> Signup and view all the answers

What is a common application of convex mirrors in retail settings?

<p>To give a wide view of the store and reduce the size of images (D)</p> Signup and view all the answers

How does an electric motor convert electrical energy into mechanical energy?

<p>By causing a coil to rotate in a magnetic field (D)</p> Signup and view all the answers

What property must be increased to enhance electricity generation when moving a magnet through a coil?

<p>The speed of the magnet's movement (C)</p> Signup and view all the answers

What is the main principle behind the operation of a generator?

<p>Transforming mechanical energy into electrical energy (B)</p> Signup and view all the answers

What type of image is formed when an object is placed between the focal point and the pole of a concave mirror?

<p>Virtual and magnified (B)</p> Signup and view all the answers

Which of the following correctly describes a convex mirror?

<p>It has a focal point behind the mirror. (A), Its reflective surface bulges towards the light source. (D)</p> Signup and view all the answers

When an object is placed at the center of curvature of a concave mirror, what type of image is formed?

<p>Real and inverted (C)</p> Signup and view all the answers

What happens to the number of images formed as the angle between two mirrors increases from 90° to 120°?

<p>The number of images decreases. (D)</p> Signup and view all the answers

What is defined as the point between the center of curvature and the vertex of a concave mirror?

<p>Focal point (B)</p> Signup and view all the answers

What type of lens is thicker in the center than at the edges?

<p>Convex lens (C)</p> Signup and view all the answers

If a light ray travels parallel to the axis of a convex lens, what happens after it strikes the lens?

<p>It travels to the axis passing through its focal point. (C)</p> Signup and view all the answers

Which characteristic of virtual images can be correctly identified?

<p>They can be upright or inverted. (A)</p> Signup and view all the answers

Flashcards

Electromagnetic Wave

A wave that consists of changing electric and magnetic fields that travel through space and can travel through materials and vacuum.

Electromagnetic Spectrum

The full range of electromagnetic waves arranged by frequency and wavelength

Radio Waves

Electromagnetic waves with the longest wavelengths and lowest frequencies in the spectrum.

Microwaves

Electromagnetic waves with wavelengths shorter than radio waves, used for cooking and communication.

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Infrared Radiation

Electromagnetic waves with wavelengths longer than visible light, often associated with heat.

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Visible Light

Electromagnetic waves that can be seen by the human eye.

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Ultraviolet Radiation

Electromagnetic waves with wavelengths shorter than visible light, often emitted by the sun.

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Wavelength

The distance between corresponding points on two successive waves.

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Concave Mirror Use in Dentistry

A concave mirror magnifies images of objects (like teeth) placed within its focal length, enabling dentists to examine them closely.

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Convex Mirror in Stores

Convex mirrors in stores provide a wider view of the store and a smaller image of shoppers.

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Convex Mirror in Side-view Mirrors

Convex mirrors in vehicles provide a wider field of view, even if images are reduced in size.

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Microscope Lens Type

A microscope uses two convex lenses (objective and eyepiece) to magnify small objects.

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Electric Motor Principle

Electric motors convert electrical energy to mechanical energy by using the interaction between an electric current and a magnetic field, causing a coil to rotate.

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Specular Reflection

Reflection of light from a smooth surface, creating a clear image.

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Convex Mirror

A spherical mirror that bulges outwards, creating a wider view.

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Focal Point (f)

The point where rays of light parallel to the principal axis converge after reflection from a concave mirror, or where they appear to diverge from after reflection from a convex mirror.

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Concave Mirror Image Formation

Images formed by concave mirrors depend on object position; if beyond focal point, real and inverted; between focal point and mirror, virtual and magnified.

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Real Image (Mirrors/Lenses)

An image that can be projected onto a screen.

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Virtual Image (Mirrors/Lenses)

An image that cannot be projected onto a screen; formed by the apparent intersection of light rays.

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Convex Lens

A lens that is thicker in the middle than at the edges, causing light rays to converge.

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Concave Mirror

A spherical mirror that curves inward, focusing incoming light.

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X-rays: Soft vs. Hard

X-rays are categorized into 'soft' and 'hard' types, with 'hard' x-rays having higher energy and shorter wavelengths, making them more penetrating.

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X-ray Applications

X-rays are used in various fields, including medical imaging to detect skeletal abnormalities and dental issues, industrial inspections to spot cracks in materials, and airport security to scan luggage.

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Gamma Rays: Source

Gamma rays are emitted by astronomical objects like the sun, interstellar clouds, and supernova remnants, making them a cosmic phenomenon.

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Gamma Ray Applications

Gamma rays have several applications, including medical treatments such as radiotherapy to target tumors, industrial uses like detecting flaws in metals, and food preservation through irradiation.

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Harmful Effects of UV Radiation

Overexposure to UV radiation can lead to skin cancer, damage to the eyes, suppression of the immune system, and reduced growth rate of plants.

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