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We'll come to very helpful blog... Chapter 5 Periodic Classification of Elements Notes class 10.. Early Models of Periodic Table Dobereiner’s Triads Dobereiner arranged a group of three elements with similar properties in the order of increasing atomic masses and called it a triad. He showed that the atomic mass of the middle element is approximately the arithmetic mean of the other two. But, Dobereiner could identify only the following three triads from the elements known at that time. Assumptions and Limitations: 1. The law was applicable for elements with atomic masses up to 40. 2. Properties of new elements discovered did not fit into the law of octaves. 3. In a few cases, Newlands placed two elements in the same slot to fit elements in the table. 4. He also grouped unlike elements under the same slot. Mendeleev’s Periodic Table and Law The physical and chemical properties of elements are periodic functions of their atomic weights. Features of Mendeleev...

Wellcome to very helpful blog Exercise of chapter  light and reflection.. Page No: 189 Very Short Answer Type Questions Q1. For what position of an object, a concave mirror forms a real image equal in size to the object? Answer: At the centre of curvature Q2. Where should an object be placed in front of the concave mirror so as to obtain its virtual, erect, and magnified image? Answer: The object should be placed between the pole and the focus. Q3. For which positions of the object does a concave mirror produce an inverted, magnified, and real image? Answer: When the object is placed between the focus and the centre of curvature. Q4. If an object is placed at the focus of a concave mirror, where is the image formed? Answer:  The image is obtained at infinity. Q5. If an object is at infinity in front of a concave mirror, where is the image formed? Answer: The image is formed at the focus. Q6. For what position of an object, a real and diminished image is formed by a concave mir...

We'll come to very helpful blog Exercise of  Page No: 178 Very Short Answer Type Questions Q1. Name the spherical mirror which has: a) virtual principal axis b) real principal axis Answer: a) Convex mirror b) Concave mirror Q2. Out of convex mirror and concave mirror, whose focus is situated behind the mirror? Answer: Convex mirror has its focus behind. Q3. Find the focal length of a concave mirror whose radius of curvature is 32cm. Answer: Radius of curvature, R = 32cm Focal length, f = ? We know that,  f = R/2 f = 32/2 = 16cm Q4. If the focal length of a convex mirror is 25cm, what is its radius of curvature? Answer: Focal length, f = 25cm Radius of curvature, R = ? We know that, f = R/2 R = 2f R = 50cm Q5. Fill in the following blanks with suitable words: a) Parallel rays of light are reflected by a concave mirror to a point called the …….. b) The focal length of a concave mirror is the distance from the ……… to the mirror. c) A concave mirror ….. rays of light whereas a con...

Access very helpful blog  Solutions Class 10 Physics Chapter 4 Solutions Page No: 173 Very Short Answer Type Questions Q1. What happens when a ray of light falls normally on the surface of a plane mirror? Answer: When a ray of light falls normally on the surface of a plane mirror, the angle of incidence is 0 degrees. From laws of reflection we know that angle of incidence is equal to the angle of reflection. Therefore, the angle of reflection will also be zero. Therefore, the light travels back in the same path. Q2. A ray of light is incident on a plane mirror at an angle of 30 degrees. What is the angle of reflection? Answer: We know from the laws of reflection that the angle of incidence is equal to the angle of reflection. Therefore, angle of reflection will be equal to 30 degrees. Q3. A ray of light strikes a plane mirror at an angle of 40 degrees to the mirror surface. What will be the angle of reflection? Answer: The angle to the mirror surface = 40 degrees The angle of incid...

Chapter electricity of class 10.. What is Current Electricity? Current electricity is defined as the flow of electrons from one section of the circuit to another. Electromotive Force (EMF) and Voltage: When two bodies at different potentials are linked with a wire, free electrons stream from Point 1 to Point 2, until both the objects reach the same potential, after which the current stops flowing. Until a potential difference is present throughout a conductor, current runs. From the above analogy, we can define electromotive force and voltage as follows: Electromotive Force Definition: Electromotive force is defined as the electric potential produced by either an electrochemical cell or by changing the magnetic field. Voltage Definition:  Voltage is defined as the electric potential difference between two points. Types of Current Electricity There are two types of current electricity as follows: Direct Current (DC) Alternating Current (AC) Direct Current The current electricity who...

We'll come to this web site . Class 10 chapter 2 of physics... Magnet A magnet is a material that produces a field that attracts or repels other such materials of magnetic nature. Lodestone is a naturally occurring magnet. It attracts materials like Iron, Nickel, Cobalt, etc. North and South Poles A magnet is always bipolar with poles named north and south poles. These two poles always exist together and can not be separated. North pole of a magnet is the side which points to Earth’s geographic north when it is freely suspended. Like poles repel and unlike poles attract Similar to charges, poles attract and repel. Like poles repel while unlike poles attract each other. Bar magnet A bar magnet is a rectangular object, composed of iron, steel or any form of a ferromagnetic substance, that shows permanent magnetic properties. It has two different poles, a north and a south pole such that when suspended freely, the north pole aligns itself towards the geographic north pole of the Earth...